'I called you to help but you shot my brother': Unarmed black man shot dead by California police

An unarmed black man, who reportedly had mental health issues, has been shot dead by police in California.

The man's sister says she called police for help after he 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.

Her brother was running around in the street and was almost hit by a vehicle so she said she wanted to get some help in taking him to the hospital, she said.

In a statement, police officials said two officers had responded to reports of a man walking in traffic in El Cajon, San Diego on Tuesday.

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.

During a news conference hours after the shooting, El Cajon Police Department spokesperson Jeff Davis said no weapon was found on thescene.

He did not say what exactly the man, who police say was in his 30's, pointed at the unidentified officers.

One witness who captured the incident has voluntarily handed her phone to police as evidence.

Although police have not released this footage, they did release a still from the footage showing the man stood before two officers with his arms outstretched holding an unidentified object.

There have been witnesses saying the man had his hands in the air when police shot him.

However, El Capon Police have said that the video footage they have been provided with shows he did not.

The woman who captured and posted a video of the aftermath of the incident told reporters the police asked the man to take his hands out of his pockets. But she doesn't think he would have understood their demands:

"The young man was mentally challenged, so I highly doubt he understood what was going on and then they shot him five times.

"I don't think it takes five times to shoot somebody and take them down, I don't think you're supposed to be shooting a mentally challenged person."

The shooting in the city east of San Diego occurred just three days after police in Charlotte, North Carolina shot dead unarmed black man Keith Scott on September 20.

The death of the 43-year-old father of seven and Terence Crutcher in Tulsa, Oklahoma, were the latest cases to raise questions about racial bias in US law enforcement.

Police shootings in New York, Baltimore, Chicago, Ferguson and Missouri, have triggered more than two years of mostly peaceful protests and given rise to the anti-racism Black Lives Matter movement.

It has prompted a national debate on policing ahead of the US presidential election in November.