Police in San Diego have released two sets of video footage showing the shooting of an unarmed black man by officers.
Alfred Olango is shown being confronted by two police officers before one shoots him dead on Tuesday in a car park in El Cajon.
Police claim the man had been behaving erratically at the time.
In the second video, which lasts less than 20 seconds, a woman can be heard shouting: "Officer don't shoot him!" before at least four shots ring out and she screams.
In a statement, police officials said two officers had responded to reports of a man walking in traffic.
When they arrived at the scene they said the man ignored instructions to remove his hand from his pocket and then pulled out an object and pointed it at them.
The officers then simultaneously shot and Tasered the man who died after being taken to hospital, police said.
No weapon was found at the scene, police later confirmed.
Mr Olango's sister said she called police for help after her brother started "acting not like himself" walking in the road and feared he would get hit by a vehicle.
In a video posted online by a witness, the sister can be seen crying while telling police "you killed my brother, I called you to help", adding that she called the emergency services three times for help.
The shooting occurred just three days after police in Charlotte, North Carolina, shot dead unarmed black man Keith Scott on September 20.