The man was said to be walking in and out of traffic
A mentally ill black man has been shot dead by police in a San Diego suburb after reportedly being seen walking in and out of traffic.
El Cajon Police Department spokesman Lt Rob Ransweiler said that two police officers arrived on the scene at 2.10pm on Tuesday, local time.
They were responding to reports about a man acting erratically which had been made around an hour earlier.
Police say the man refused to obey their instructions to take his hand out of his trouser pocket, paced back and forth before rapidly drawing an object from his pocket.
One minute after they had arrived on the scene, an officer shot him with a stun gun and the other fired a handgun.
Witnesses reported hearing five shots.
The victim has been identified as Alfred Olango, a 30-year-old refugee from Uganda who was described by a fellow refugee Agnes Hassan as well-educated but mentally ill.
It is understood that Mr Olango's sister had called police to say he had been behaving strangely but that she had also warned them he had mental health difficulties.
Christopher Rice-Wilson, associate director of civil rights group Alliance San Diego, asked why one officer felt non-lethal force was appropriate while the other did not.
Protesters gathered outside El Cajon's police headquarters on Wednesday chanting "killer cops" and "black lives matter".
A woman who identified herself as Mr Olango's sister said in a video posted on Facebook that she had called police for help for her brother, saying: "I just called for help and you came and killed him".
El Cajon Police Chief Jeff Davis has urged the community to stay calm, adding: "This (investigation) will be transparent. This will be looked at by multiple sets of eyes and not just ours".
El Cajon police officers do not wear body cameras.
Both officers, each with more than 20 years in the force, are on administrative leave while the shooting is investigated.
The shooting is the latest of black men at the hands of police officers, the most recent being the death of Keith Lamont Scott, a 43-year-old father in the North Carolina city of Charlotte.
Also on Wednesday, a teenager killed his father at their home before opening fire at Townville Elementary School in South Carolina, injuring two students and a teacher.
The victim was identified as Jeffrey DeWitt Osborne, 47. Two of those injured - the teacher and a pupil - have been released from hospital, while the second pupil Jacob Hall, six, is in a critical condition.
The teenager, reportedly aged 14, was arrested without incident and police said the shooting had no apparent racial or terrorist motivations, nor did the shooter have any obvious connection to the school, as he is home-schooled.