Matthew Riehl, 37, was identified as the gunman who allegedly killed one deputy and injured four others in the Sunday shooting

The gunman, who allegedly killed a deputy and injured four other officers after firing 100 rounds in an 'ambush attack' in Colorado, was an Iraq War veteran who posted a YouTube video earlier this month claiming he was trying to unseat his local sheriff.

Matthew Riehl, 37, was identified as the gunman by local news station Denver 7, which cited 'two informed law enforcement sources'.

During the Sunday morning attack deputy Zackari Parrish, 29, was shot dead while responding to a verbal disturbance call around 5.15am.

Deputy Mike Doyle, 28, Deputy Taylor Davis, 30, Deputy Jeffrey Pelle, 32, - all of the Douglas County Sheriff's Office - and 41-year-old Castle Rock Police Officer Tom O'Donnell were injured.

Douglas County Sheriff Tony Spurlock revealed at a press conference Sunday afternoon that all of the officers are in stable condition.

Authorities publicly identified Riehl, who was shot dead by a joint task force unit, on S.

Just two weeks ago, Riehl, recorded himself ranting about one of the Douglas County Sheriff's deputies, Brian Briggs.

Scroll down for video

Just two weeks ago, Riehl (left and right), recorded himself ranting about one of the Douglas County Sheriff's deputies, Brian Briggs. In the bizarre YouTube video, Riehl can be seen holding up Briggs' business card as he calls him a 'pimp' multiple times

Riehl was deployed to Iraq from 2009-2010. He was honorably discharged in 2012 after nine years of service in the Army Reserve

In the bizarre YouTube video, Riehl can be seen holding up Briggs' business card as he calls him a 'pimp' multiple times.

Riehl then goes on to lash out at Sheriff Spurlock, calling him and his deputies 'clowns'.

'We're going to fire all these bums come next year,' Riehl is heard saying as he promotes his 'Libertarian' candidacy for the sheriff of Douglas County.

Riehl was deployed to Iraq from 2009-2010. He was honorably discharged in 2012 after nine years of service in the Army Reserve.

According to News 9, the YouTube video wasn't the first time Riehl lashed out at the sheriff's office.

He also reportedly exchanged a series of angry tweets with the Douglas Sheriff's Office.

During Sheriff Spurlock's press conference Sunday afternoon, he did say that officers 'are familiar with him [the suspect]'.

Deputy Zackari Parrish, 29 (pictured) was shot and killed while responding to a verbal disturbance at an apartment complex near Denver. He is survived by his wife and two young daughters

Four other deputies were shot. They include 28-year-old Deputy Mike Doyle (left), 30-year-old Deputy Taylor Davis, 32-year-old Deputy Jeffrey Pelle - all of the Douglas County Sheriff's Office - and 41-year-old Castle Rock Police Officer Tom O'Donnell (right)

Deputy Jeffrey Pelle (left), son of Boulder County Sheriff Joe Pelle, was confirmed as one of the deputies shot this morning, according to the Boulder County Sheriff’s Office

After the tragic shooting, a motorcade was held for fallen deputy Parrish.

A line of police cars left Littleton Adventist Hospital and traveled along Colorado State Highway 470 led by two officers on motorcycles.

Deputy Taylor Davis, 30, is also among the officers who were injured in the shooting

Some stood and saluted as the hearse passed by while others held up American flags in honor of the deceased deputy.

Parrish was one of five deputies who was shot while responding to a verbal disturbance call between two roommates around 5.15am on Sunday at the Copper Canyon Apartments on the 3400 block County Line Road between Colorado and University Boulevards.

The Douglas County Sheriff's Office tweeted that it was during the investigation at the building in Highlands Ranch that shots were fired with a rifle - nearly 100 rounds in an ambush-style attack.

Two civilians were also shot by the suspect, but sustained non-life-threatening injuries.

They have not been identified.

On Sunday afternoon, President Donald Trump sent a message of sympathy, tweeting: 'My deepest condolences to the victims of the terrible shooting in Douglas County @DCSheriff, and their families.

'We love our police and law enforcement - God Bless them all! #LESM,' the president tweeted.

A motorcade (pictured) was held for a Parrish after he was shot and killed in the line of duty

A line of police cars left Littleton Adventist Hospital (pictured) and traveled along Colorado State Highway 470 led by two officers on motorcycles

A procession of police vehicles escorts the hearse carrying the body of Parrish, who was killed on Sunday morning.

Members of the fire department salute as the motorcade drives by (pictured). Parrish was one of five who were shot at an apartment complex near Denver

Sheriff Spurlock said the officers responded to a call that came in as a domestic dispute but was quickly revealed to be a verbal dispute between the shooter and his roommate.

It was the second time deputies had gone to the apartment Sunday.

There was another call at about 1.30am but there was no noise when deputies arrived.

After being let in, and confronting the suspect, who had barricaded himself in a bedroom, the officers were almost immediately met with fire.

The sheriff said there is no timeline available yet as to who was shot first but that all of them were shot 'very very quickly and all went down within seconds of other'.

David Morgan of Highlands Ranch, holds an American flag as a procession of law enforcement vehicles accompany a hearse carrying Parrish's body

The Douglas County Sheriff's Office said the deputies were responding to a domestic disturbance call around 5.15am Sunday at the Copper Canyon Apartments on the 3400 block County Line Road between Colorado and University Boulevards

It was during the investigation at the Highlands Ranch building that shots were fired and several deputies were injured, the sheriff's office tweeted (scene above)

On Sunday afternoon, President Donald Trump sent a message of sympathy to the victims of the shooting

The four were able to crawl to safety while a separate joint task force unit entered the apartment and eventually shot and killed Riehl.

Authorities said the roommate, who was home, was not injured and the two civilians were not in the apartment.

Parrish is survived by his wife and two young daughters and a GoFundMe account has been set up to help support them.

So far, $123,126 has been raised.

According to WBPF, a sheriff's office spokesperson confirmed that a SWAT team arrived at the home where the shooting occurred around 7.15am.

Sheriff Spurlock said the officers responded to a call that came in as a domestic dispute but was quickly revealed to be a verbal dispute between the shooter and his roommate (Pictured, Mike Doyle)

After being let in, and confronting the suspect, who had barricaded himself in a bedroom, the officers were almost immediately met with fire (Pictured, Tom O'Donnell)

The sheriff said there is no timeline available yet as to who was shot first but that all of them were shot 'very very quickly and all went down within seconds of other' (Pictured, Jeffrey Pelle)

The four - aside from Parrish (pictured with and two young daughters) - were able to crawl to safety while a separate joint task force unit entered the apartment and eventually shot and killed the suspect

A GoFundMe account has been set up to help support Parrish's family (pictured with his two daughters in August 2016)

Video broadcast by Denver 7 showed an Arapahoe County Sheriff Bomb Squad truck at the scene.

The sheriff's office earlier issued a 'Code Red' on Twitter, instructing residents in the area to shelter in place.

'A Code Red was sent out regarding this incident. Any citizens in the affected area are instructed to shelter in place, avoid windows and stay away from exterior walls,' read the post sent out around 6.15am local time.

Much remains unclear about Riehl’s life and his actions leading up to the shooting, but he did have an interest in guns.

Photos on Riehl's Facebook page show him posing with a few weapons. According to the New York Times, Riehl took an introductory course in carbine rifles in June.

The course was run a company called Kenaz Tactical Group, according to Robert Butler, the company’s owner and lead instructor.

Butler said Riehl seemed like 'just the ordinary student' and did not seem unstable or violent.

Much remains unclear about Riehl’s life and his actions leading up to the shooting, but he did have an interest in guns. Photos on Riehl's Facebook page show him posing with a few weapons

According to the New York Times, Riehl took an introductory course in carbine rifles in June

Linda Watson, a spokesperson for Sky Ridge Medical Center in Lonetree, told The New York Times that the hospital received three patients who are all in non-critical condition.

However, she did not specify whether these were law enforcement officers or civilians.

Another four were taken to Littleton Adventist Hospital in Littleton, Alyssa Parker, a hospital spokeswoman, told the newspaper. She did not specify how serious the injuries were.

In updating its Facebook and Twitter pages with the news of the deputy’s death, the Sheriff’s Office changed its profile images to a badge with a black band across it.

In updating its Facebook and Twitter pages with the news of the deputy’s death, the Sheriff’s Office changed its profile images to a badge with a black band (pictured) across it

Two civilians were also shot by the suspect. Pictured is a map of where the shooting took place

Video also showed a Arapahoe County Sheriff Bomb Squad truck outside the complex (scene above)

The office had reported 'multiple deputies down' after the shooting, which happened in Highlands Ranch, about 15 miles south of Denver

The sheriff's office has issued a 'Code Red' on Twitter, instructing residents in the area to shelter in place

Linda Watson, a spokesperson for Sky Ridge Medical Center, told The New York Times that the hospital received three patients all in non-critical condition but she did not specify whether these were law enforcement officers or civilians (Pictured, aerial map of the shooting location)

Denver7's Meghan Lopez arrived on scene and reported hearing gunshots ring out in the distance.

She also noted several roads were closed in the area due to the police response and that at least eight ambulances were at the scene earlier Sunday.

The Sheriff's Office also issued a tweet stating that Douglas County, Parker Police Department, Lone Tree Police Department, Castle Rock Police Department and Colorado State Patrol were all agencies on 'accident alert'.

Four of the victims - including the deceased deputy - were taken to Littleton Adventist Hospital in Littleton, Alyssa Parker, a hospital spokeswoman, said. First responders at the scene early Sunday morning

The Copper Canyon Apartments website describes its homes (pictured) as some of the 'friendliest apartments in Highlands Ranch,' minutes away from shopping, dining and entertainment in Denver

Around 9am, an emergency shelter was set up at the Highlands Ranch Recreation Center at Eastridge at 9568 University Boulevard for anyone displaced from their home during the investigation.

The Copper Canyon Apartments website describes its homes as some of the 'friendliest apartments in Highlands Ranch,' minutes away from shopping, dining and entertainment in Denver.

Highlands Ranch is an affluent neighborhood in Colorado with the median income for a household at $104,411, and the median income for a family at $113,944.

Only about one per cent of families in the area live below the poverty line.