In this Saturday, Aug. 1, 2015, photo, Memphis police officers gather at Regional Medical Center in Memphis, Tenn., after officer Sean Bolton was fatally shot during a traffic stop in Memphis.
Photo by Mark Weber/The Commercial Appeal/AP

Tremaine Wilbourn hunted over shooting of Memphis police officer Sean Bolton

A gunman was on the loose early Monday following the fatal shooting of a Memphis police officer, authorities said.

Officer Sean Bolton, 33, was shot multiple times during a traffic stop in southeast Memphis on Saturday night, officials said. Police said that a civilian used an officer’s radio to report the shooting.

The driver of the vehicle later turned himself in to the police and was then released without charge. The passenger of the vehicle, who is believed to be the shooter, has been identified as 29-year-old Tremaine Wilbourn, police said.

Wilbourn is still at large and a warrant for 1st degree murder has been issued for his arrest, officials said.

Related: Officer Sean Bolton shot and killed during traffic stop

The suspect was already out on supervised release following a 10-month sentence for bank robbery, police said. He is considered to be armed and dangerous.

Bolton, a five-year veteran of the force, was rushed to the hospital in critical condition, and later died from his wounds, according to police. The Associated Press reported he was a U.S. Marine Corps veteran who had served a tour of duty in Iraq.

Bolton was wearing a bullet-proof vest but not a body camera, Memphis Police spokeswoman Karen Rudolph told NBC News on Sunday. Authorities were asking for potential witnesses to come forward with any information they might have about the deadly incident.

Memphis Director of Police Services Toney Armstrong has said the shooting was the third time a city officer has been killed in the line of duty in the last four years.

“As I have said many times, to lose a loved one or a family member is a horrific event. Last night we lost not only an officer, but a great man, a dedicated servant to our community, and a family member,” Armstrong said in a statement.

“As I mentioned last night, we as a community must come together and remember that ALL LIVES MATTER, not just Black lives or just White lives … ALL LIVES matter.”

This story originally appeared on NBCNews.com

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Tremaine Wilbourn hunted over shooting of Memphis police officer Sean Bolton