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Edward Crawford, a St. Louis resident who was the subject of an iconic photo epitomizing the 2014 protests in Ferguson, Missouri, is dead.

Crawford was photographed throwing a flaming tear gas canister in an image broadcast widely during the months of unrest that followed the fatal shooting of Michael Brown Jr. by a police officer.

His death was confirmed to NBC News by the St. Louis Office of the Medical Examiner. Investigator Rose Psara said Crawford was pronounced deceased shortly before midnight on Thursday at 1435 Salisbury Street in the Hyde Park neighborhood.

Related: Darren Seals, Ferguson Protest Leader, Found Fatally Shot in Burning Vehicle

The St. Louis Metropolitan Police Department told NBC News that Crawford shot himself in the backseat of a car while it was moving, according to two witnesses who were seated in the front of the car.

Edward Crawford returns a tear gas canister fired by police who were trying to disperse protesters in Ferguson, Mo. on Aug. 13, 2014. Robert Cohen / St. Louis Post-Dispatch via Zuma Press

"The victim began expressing he was distraught over personal matters to the witnesses," said the police department's Public Information Officer Leah Freeman. "The witnesses heard the victim rummaging in the backseat, then heard a gunshot and observed the victim had sustained a gunshot wound to the head."

Crawford was pronounced dead on the scene. Police said an investigation is ongoing and, while initially declared a suicide, the official cause of death will be determined by an autopsy.

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Related: Federal Judge Dismisses Excessive Force Lawsuit Against Police During Ferguson Protests

According to his father, Edward Crawford Sr., the 27-year-old was the father of four young children, had just gotten a new apartment, and was training for a warehouse job.

"I don't believe it was a suicide," the senior Crawford told the St. Louis Post-Dispatch, which first reported the death on Friday morning.

Edward Crawford in a combo selfie posted on his Twitter account on June 28, 2015. Twitter

It's not the first time a notable Ferguson protester has died from gunfire.

In September 2016, the body of Ferguson activist Darren Seals was discovered inside a burning car. Seals had been shot, and police declared the death a homicide.

Related: Ferguson Security Video Renews Anger Over Michael Brown’s Death

In November 2014 on the night a grand jury declined to convict the Ferguson police officer who fatally shot Brown, 20-year-old Deandre Joshua was found shot in the head with severe burns after being lit on fire. Like Seals, Joshua was discovered dead in his own car.

NBC News sent several requests for comment about the death of Edward Crawford to the St. Louis Police Department but did not receive a response.

It is unclear where Crawford's body was found.

On social media, notable leaders of the Black Lives Matter movement and the St. Louis community mourned Crawford's death.

Missouri State Sen. Maria Chappelle-Nadal said that Crawford was a local hero after he famously picked up the tear gas canister and threw it out of the way of protesters.

Edward Crawford is dead. Found in his car shot to death. He is #Ferguson's hero. For those of us tear-gassed, he was our local champion. RIP pic.twitter.com/RHtBEB174G — MariaChappelleNadal (@MariaChappelleN) May 5, 2017

In the photograph, which won the Pulitzer Prize for breaking news photography in 2015, Crawford appeared to be throwing the canister back at police while wearing a shirt emblazoned with an American flag. The photo came to symbolize anger at police killings of unarmed black youth.

He was later charged for assault and for interfering with a police officer in relation to the tear gas incident.

Crawford posted a photo on his Twitter profile in September 2015 showing him posing next to his iconic image at the offices of the St. Louis Post-Dispatch.

But Crawford told the St. Louis Post-Dispatch in 2015 that he was trying to protect people from the tear gas. and that police were 30 or 40 yards away: "“I can’t even throw a baseball that far, let alone a burning can of tear gas."

"I didn’t throw a burning can back at police," said Crawford. "I threw it out of the way of children."