El CAJON, Calif. -- What started as a peaceful vigil Wednesday at the site where police fatally shot an unarmed black man the day before quickly got tense when a man identifying himself as a Donald Trump supporter infiltrated the crowd, reports CBS San Diego affiliate KFMB-TV.

For a second straight day, demonstrators in this San Diego suburb were demanding answers about the death of Ugandan refugee Alfred Olango.

The purported Trump backer, who was wearing a “Make America Great Again” cap -- the slogan of Trump’s campaign -- later claimed to reporters that he was “cornered, I was beaten to the ground. When I attempted to run away, I was chased by the entire mob of people.”

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Police arrived quickly to try to disperse the crowd as tensions mounted, KFMB says.

From there, the protesters -- roughly 200 -- took to the streets of El Cajon, demanding justice for Olango, who they said was mentally ill. They were chanting “no justice, no peace, no racist police!”

At times, the demonstrators blocked traffic. California Highway Patrol officers in riot gear, some with dogs, blocked freeway entrances. Some officers faced off with protesters occasionally, but mostly kept their distance.

The protests were peaceful for the most part.

Demonstrators in El Cajon, California on September 28, 2016 demanding answers about the fatal police shooting the day before of a Ugandan refugee KFMB-TV

But the protesters insisted they won’t back down.

One told KFMB, “This isn’t going to go away. We’re going to keep doing this as long as it takes.”

Olango had a history of run-ins with authorities and was distraught over the recent death of his best friend.

He was having an emotional breakdown over his friend’s death when police confronted him, said attorney Dan Gilleon, who says he’s representing Olango’s family.

Authorities said it took more than an hour for police to arrive at the shopping center where Olango had been wandering into traffic. It took about a minute for him to be shot and killed.

Olango pulled a large electronic cigarette,known as a vape pen, from his pocket and pointed in a “shooting stance” at the police officer who fired, while a second officer stood nearby trying to subdue him with a stun gun, El Cajon police said.

The details emerged Wednesday.

The investigation centered on a video of Tuesday’s shooting taken by a bystander. Police have produced a single frame from the cellphone video to support their account, saying it shows Olango in the “shooting stance.”

The photo shows Olango’s hands clasped together and pointed directly at an officer who had assumed a similar posture with his gun a few feet away.

The vaping device in his hands had two components, a box about the size of a cellphone and a metallic cylinder that was 3 inches long and 1 inch wide. Police said the cylinder was pointed right at the officer.

Olango’s relatives demanded the full video be released, according to Gilleon.

“They’re cherry-picking part of the video,” Gilleon said. “This is exactly what police have said is unfair -- when only portions of video are released against them.”

Mayor Bill Wells said he had seen the video and that it was not “tremendously complicated to figure out what happened.”

Wells was asked how he would feel if it was his child that had been shot.

“I saw a man who was distraught, and a man acting like he was in great pain,” Wells said. “And I saw him get gunned down and killed. If he was my son, I would be devastated.”

Olango, 38, arrived in the U.S. years ago from Uganda. Since then, he ran afoul of the law several times: selling cocaine, driving drunk, and illegally possessing a 9mm semi-automatic handgun when he was arrested in Colorado in 2005 with pot and ecstasy in his car, according to court records. He pleaded guilty in federal court and was sentenced to nearly four years for being a felon in possession of a gun.

The fatal shooting happened less than two weeks after black men were shot and killed by police in Tulsa, Oklahoma, and Charlotte, North Carolina, where violent protests broke out​.

Experts said it was too early to conclude whether the California shooting was justified or could have been prevented.

Chuck Drago, a former Florida police chief who consults about police use of force, said that once Olango struck the shooting pose, officers would have had to react quickly if he drew an unknown object from his pocket.

“An officer doesn’t have enough time to wait to determine if that’s a gun in his hand,” Drago said. “If a person is pointing something at an officer and he believes it’s a gun and it is a gun and that officer doesn’t have his gun out, that officer will lose that gunfight.”

Police haven’t named the officers involved, though Wells said both were 21-year veterans and one was Officer Richard Gonsalves.

Gonsalves was demoted last year after allegations that he sexually harassed a lesbian colleague. The City Council had to defend the move to angry citizens who had called for him to be fired.

Christopher Rice-Wilson, associate director of the civil rights group Alliance San Diego, questioned why one officer felt non-lethal force was appropriate while the other did not. Both officers have been put on administrative leave while the incident is investigated, per department policy. Officials have not revealed which officer fired the shots.

El Cajon, a city of 100,000 people about 15 miles northeast of San Diego, has become home for many refugees fleeing Iraq and, more recently, Syria.