Police sources said Officer Liang is left-handed. He had a flashlight in his right hand and the gun in his left, sources said.

He was trying to open a door that swings open into the stairwell, and he turned the door handle with the gun in his hand, police sources said.

At that point, the gun went off accidentally, sources said.

“It’s far safer than picking up your phone or trying to fumble with your phone.”

After the shot was fired, the officers retreated from the staircase back into the hallway, sources told CBS2. They reentered the dark staircase unaware that anyone had been hit by the bullet, sources said.

Bratton: Fatal Police-Involved Shooting Of Unarmed Man At Brooklyn Housing Complex ‘Unfortunate Tragedy’

Gurley’s girlfriend said he was ahead of her when he was shot, sources said. She said she heard the shot and ran downstairs, and at one point, Gurley was behind her also running, sources said.

The girlfriend lost sight of Gurley on the fourth floor, and went back upstairs to find him collapsed on the fifth floor, sources said. She then ran to a neighbor, who called 911, sources said.

Within four minutes, an EMT arrived at the scene to find the girlfriend performing CPR on Gurley, sources said. The 911 call from the neighbor had already been placed before the officers arrived on the fifth floor, but a police radio call of an accidental discharge and a man shot was relayed later after a lieutenant arrived, sources said.

Because the officers did not initially realize that the shot had hit anyone, there was about a five-minute delay in their radio call of a man shot, sources said.

Police said the first 911 call came in at 11:15 p.m. and the ambulance was dispatched a minute later. At 11:19 p.m., the police lieutenant and supervisor arrived on the scene.

But it was after that, at 11:20 p.m., when Liang and his partner radioed for help.

The family of Gurley’s girlfriend, Melissa Butler, also told 1010 WINS’ Glenn Schuck that by her account, the officers said nothing at the time the gun went off.

Why Officer Liang had his gun drawn along with a flashlight in the first place was to be a question for him, and police late Friday had not yet been able to speak with him because of union rules.

But as WCBS 880’s Irene Cornell reported, Bratton emphasized that police believe there was every indication that he never intended to fire a shot at all.

“Let me reinforce – at this point, the deceased is, based on our preliminary investigation, totally innocent,” Bratton said. “(He) just happened to be in that hallway as the officers were entering the adjacent hallway one landing up; was not engaged in any criminal activity of any type.”

Bratton said Friday that Liang had his gun and flashlight out prior to the shooting “for safety reasons” in the darkened stairwell.

“We leave that decision as to when to take a firearm out at the discretion of the officer based on what they encounter or believe they may encounter, so there is not a specific prohibition against taking a firearm out,” Bratton said.

The second officer did not draw his weapon, Bratton said.

“What happened last night was a very unfortunate tragedy,” Bratton said.

He said Gurley and his girlfriend had tried to get an elevator, but it was delayed so they decided to take the stairs instead.

“The deceased was not engaged in any activity other than trying to walk down the stairwell,” Bratton said.