Los Angeles, US: Protesters marched on Wednesday in a California town following the fatal police shooting of an unarmed black man said to be mentally ill, as local officials urged calm and pledged a full investigation.

Alfred Okwera Olango, 38, was shot on Tuesday in the San Diego suburb of El Cajon after police received an emergency call about a man behaving erratically and walking in traffic.

El Cajon police chief Jeff Davis said Olango had ignored repeated calls by responding officers to remove his hand from his pocket and one officer used a taser against him while another fired his weapon when he turned and confronted them.

‘At one point, the subject rapidly drew an object from his front pants pocket, placed both hands together and extended them rapidly toward the officer taking up what appeared to be a shooting stance,’ Davis said in a statement. ‘At this time, the officer with the electronic control device discharged his weapon.

‘Simultaneously, the officer with the firearm discharged his weapon several times, striking the subject.’

Authorities said Wednesday the object that Olango had in his hands was a ‘vape’ electronic cigarette. It had a silver cylinder and Olango held the vape’s box in his grip.

The shooting took place as the United States reels from a string of police killings of black men that have raised racial tensions nationwide.

Dozens of angry demonstrators marched peacefully on Wednesday in El Cajon, a town with a large immigrant and refugee population, at one point blocking an intersection as they faced off with police in riot gear.

‘These senseless killings have to stop—not just in El Cajon but in the entire country,’ community activist Estela De Los Rios said.

More than 100 people had gathered Tuesday evening at the scene of the shooting insisting that it was unjustified and racially motivated. Several shouted ‘black lives matter’ and ‘hands up, don’t shoot.’

Police urge calm

Local officials have urged residents to remain calm, pledging that the incident would be fully investigated by police, the district attorney and the FBI.

‘This will be transparent. This will be looked at by multiple sets of eyes, and not just ours,’ Davis vowed at a news conference.

Police have also released a still photo lifted from a video taken at the scene that shows a man in a shooting stance.

One witness posted a Facebook Live video after the shooting that showed a distraught woman who identified herself as Olango’s sister and said she had called police to help her brother who was mentally ill.

‘You guys came and killed my brother,’ the woman wails in the video that had been viewed more than 110,000 times by Wednesday afternoon.

‘I called you guys to help my brother. You killed my brother in front of me.’

Relatives said Olango was a refugee from Uganda.

Davis said the two officers involved in the shooting, each with more than 20 years of service, had been placed on administrative leave pending the outcome of the investigation.

The deaths of black men at the hands of police have spurred protests across America, most recently last week in the North Carolina city of Charlotte.

The fatal shooting of Keith Lamont Scott, 43, triggered days of unrest, forcing the governor to declare a state of emergency and deploy the National Guard.