Community members and activists are gathering at Sacramento City Hall on Thursday to protest the fatal shooting of an unarmed Black man by police.

Black Lives Matter Sacramento is organizing the rally in honor of Stephon Clark, a 22-year-old who was shot Sunday night in his grandparents’ backyard, where he was staying.

Sequita Thompson recounts the horror of seeing her grandson Stephan Clark dead in her backyard after he was shot by police in Sacramento, Calif. Relatives, activists and Sacramento officials are questioning why police shot at an unarmed Black man 20 times, killing him, when he turned out to be holding only a cellphone in his grandparents’ backyard. (Renee C. Byer/The Sacramento Bee via AP)

The two officers yelled that they thought he had a gun in the moments before they shot him, according to audio from body camera footage released Wednesday by Sacramento police. But Clark was only holding a cellphone.

(WARNING: This video may contain graphic images and/or profane language.)

Footage from body cameras and an overhead helicopter does not clearly depict what Clark was doing just before police opened fire. Officers did not find a gun at the scene.

The Sacramento Police Department said they were responding to reports of a man seen breaking into at least three vehicles and later into a neighbor’s home. The break-ins were first reported by a 911 call also released by the police.

The police said deputies in the helicopter saw Clark break a neighbor’s sliding glass door before jumping a fence. The helicopter video does not show the alleged break-in. It picks up as he is running through a backyard and climbing over a fence into a neighboring property. It shows him looking into a truck in the driveway.

The helicopter, flying over the house, then loses sight of the man. It briefly shows him in the backyard as the police are running up the driveway along the side of the house.

“Show me your hands — gun!” one officer yells, according to the body camera footage released Wednesday. It is dark outside and a flashlight from one body camera briefly shows the backyard, but the man is not visible. “Gun, gun, gun,” one of the officers yells before they begin shooting.

The helicopter footage shows Clark collapsing as they shoot. It’s unclear from the helicopter and body camera video exactly how many shots were fired. Police previously said the officers fired 20 shots.

The department had said he advanced toward the officers holding an object extended in front of him. The officers thought he was pointing a handgun, police said.

After the shooting, the footage shows the officers taking turns reloading and keeping their guns trained on the man from a distance while they await backup.

When backup arrives, one of the officers who fired says, “We can’t see his left hand.” Someone suggests getting a nonlethal weapon before approaching.

“Let’s hit him a couple of times with that before we uh–” the officer says, though it appears the suggestion was heeded.

“What’d he have on him?” someone asks.

“Something in his hands, it looked like a gun from our perspective,” one officer says.

As several officers approach, the man is seen lying face down with a cellphone near his head. He’s handcuffed and the officers discuss performing CPR.

The officers who fired are taken to the street, where someone says “Hey mute” and the audio cuts out. The video continues without sound for about two minutes as the officers talk.

“Based on the videos alone, I cannot second guess the split-second decisions of our officers and I’m not going to do that,” Mayor Darrell Steinberg said in a statement. “The investigation must be completed. We need more information in addition to the video before we can render any final conclusions.”

Steinberg said appropriate questions have been raised about the protocols for using force and rendering emergency aid during police shootings and they must be answered in the investigation.

The shooting has ignited questions by relatives, activists and others after it turned out he was holding only a cellphone.

.Salena Manni, who identified herself as Clark’s fiancee, said he was the father of her two sons, ages 1 and 3.

“He would never want to leave his kids,” Manni said in an interview with ABC10. “I just tell them daddy’s always going to be with us, daddy’s in our hearts, always and forever. He’s always going to be with us. Don’t forget that.”

Clark routinely helped care for his grandparents at their home in south Sacramento, his cousin, Sonia Lewis, told Capitol Public Radio.

Black Lives Matter Sacramento called it a police murder and demanded answers. City Councilman Larry Carr decried the loss of life and said police must provide timely information.

The department said the two officers have been with Sacramento police for two and four years, but each has four years’ previous experience with other law enforcement agencies. Both are on paid administrative leave.