SAN FRANCISCO (CBS SF) – At a town hall meeting Thursday night in San Francisco, police released more details in the shooting of a mentally disturbed person last week in the Lake Shore neighborhood and the condition of a police officer shot in the head that night.

Police Chief Toney Chaplin gave about 50 residents and others attending the 6 p.m. meeting at the Scottish Rite Masonic Center at 2850 19th Ave. an update on the investigation and took questions from a relatively calm crowd.

READ MORE: Former Presidential Candidate Andrew Yang Touts Basic Income at Mountain View Rally

The suspect in the shooting, Nicholas McWherter, opened fire on police as they arrived to a report of a disturbance Friday night at the Big 5 Sporting Goods store at 1533 Sloat Blvd.

At least one bullet hit police Officer Kevin Downs in the head, nearly hitting an artery that could have killed him.

The injury prompted an emergency call to other police officers who responded and eventually shot McWherter as he fired at other officers.  McWherter died from his wounds Sunday at San Francisco General Hospital.

Chaplin said police responded at 8:10 p.m. to the Big 5 Sporting Goods store on a report of someone threatening customers and trying to instigate a fight. Later police learned that McWherter was trying to instigate a fight with a security guard who pepper-sprayed McWherter without success, Chaplin said.

Four minutes later officers arrived and McWherter opened fire, hitting Downs.

“So the shooting happened almost instantly,” Chaplin said.

Police were not aware that McWherter had a gun. He has no previous arrest history in San Francisco, a police spokesman said. Police have determined how McWherter got the gun, but they are not releasing that information yet.

McWherter ran to Sigmund Stern Recreation Grove and encountered police again at 28th Avenue and Vicente Street where he tried to run from police. Officers pursued him and in a wooded area McWherter fired at officers. Officers returned fire and hit McWherter four times.

READ MORE: National Park Service Proposes Parking Fees at Popular Bay Area Beaches

Despite officers’ commands to drop his gun, McWherter allegedly kept it to his chest as he lay on the ground. Police deployed flash-bang devices to distract him and take him into custody before he was transported to San Francisco General Hospital with critical injuries.

Chaplin said it was 20 minutes from the time McWherter opened fire on Downs to the time he was arrested.

San Francisco police recently deployed body-worn cameras in response to numerous officer-involved shootings that led to the departure of police Chief Greg Suhr. But the two officers who shot McWherter did not have their cameras.

Police spokesman Sgt. Michael Andraychak said the two officers were not wearing their cameras because they had just finished their shifts and turned in their equipment when they responded to the shooting of Downs.

The two officers fired 21 rounds at McWherter and hit him four times.

Four investigations have been opened into the shooting. The San Francisco Police Department has opened both an administrative and criminal investigation and both the Office of Citizen Complaints and the San Francisco District Attorney’s Office have opened investigations.

Downs is expected to survive. His family released information saying the bullet fractured his skull and missed a main artery by less than a centimeter. The fracture caused trauma to his brain, which has left him paralyzed in his right leg. On Sunday, police said part of one side of his body was paralyzed, but he has since regained some movement in his right arm, Chaplin said.

Chaplin identified McWherter as a mentally disturbed person and he said police want mental health specialists to be the first point of contact in similar situations.

“It’s a national issue,” he said.

MORE NEWS: CVS Stores Roll Out Pfizer Booster Shots Across Bay Area

© Copyright 2016 by CBS San Francisco and Bay City News Service. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.