BERKELEY, Mo. -- Protesters took to the streets of a St. Louis suburb on Wednesday night, one night after the fatal shooting of an 18-year-old black man by a white police officer.

Authorities said Antonio Martin was shot and killed late Tuesday after pointing a 9 mm handgun at the officer who was questioning him and another man about a theft at a convenience store.

Antonio Martin is pictured in two 2013 mugshots released by the St. Louis Metropolitan Police Department. St. Louis MPD

The officer stumbled backward but fired three shots, one of which struck Martin, St. Louis County Police Chief Jon Belmar said. No shots came from Martin's loaded gun, the chief said.

Martin died at the scene, though Belmar declined to specify where the fatal bullet hit Martin. The store's surveillance cameras captured the confrontation from several angles.

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Although the shooting took place only two miles from Ferguson, where a white police officer shot and killed 18-year-old Michael Brown, officials said the circumstances were starkly different.

"You couldn't even compare this with Ferguson or the Garner case in New York," Berkeley Mayor Theodore Hoskins said, referring to the chokehold death of Eric Garner, another black man killed by a white police officer.

The mayor said the video footage appears to support the officer's claim that he fired in self-defense.

Hoskins, who is black, also noted that unlike in Ferguson -- where a mostly white police force serves a mostly black community -- more than half of the officers in his city of 9,000 are black, including top command staff.

Shortly after the shooting, a crowd of about 300 people gathered at the gas station, throwing rocks and bricks in a scene reminiscent of the sometimes-violent protests that followed Brown's death.

More than 50 police officers, some in riot gear, responded. Video showed some wrestling with protesters. Belmar said officers used pepper spray but not tear gas. Four people were arrested on charges of assaulting officers.

Belmar said three explosive devices, perhaps fireworks, were tossed near gas pumps, and some protesters threw rocks and bricks. One officer hit by a brick was treated for facial cuts, and another was treated for a leg injury sustained as he retreated from an explosive.

Police said several explosive devices, possibly fireworks, were thrown after a crowd gathered at a gas station on Dec. 24, 2014, hours after an officer shot and killed an armed 18-year-old man in Berkeley, Missouri. KMOV

Wednesday night, a smaller group of protesters marched down Interstate 170 before staging a "die-in" outside the convenience store amid a strong police presence.

CBS affiliate KMOV in St. Louis reported Martin had faced several criminal charges in the last few years, including three assaults, an armed robbery, unlawful use of a weapon, armed criminal action and theft.

Martin was sentenced to 30 days in jail after pleading guilty to a theft charge in November 2013, according to the St. Louis Metropolitan Police Department. He had been expelled from Jennings High School.

"[He was] trying to get his life back together," Toni Martin-Green told KMOV. "We were trying to get him back in school. He was waiting to get back into job corps."

The 34-year-old officer, a six-year veteran of the Berkeley Police Department whose name has not been released, is on administrative leave while St. Louis County police and the city of Berkeley conduct separate investigations.

Belmar called the shooting a tragedy for both Martin's family and the officer.

"He will carry the weight of this for the rest of his life, certainly for the rest of his career," Belmar said of the officer. "There are no winners here."

Belmar said the officer wasn't wearing his body camera and the dashboard camera was not activated because the patrol car's emergency lights were not on.

Mayor Hoskins said he was willing to overlook the fact the officer wasn't wearing the camera, CBS radio station KMOX reported.

"We're in the process of trying to implement that. We only have three," Hoskins said. "If it had been six months from today, and we've gone through all of the training, I would have some concern."

In fact, Hoskins said at that point, it will bring about "severe penalties."

Martin's death was the third fatal shooting of a young black man by a white police officer in the St. Louis area since Brown was killed by Ferguson officer Darren Wilson on Aug. 9.

Kajieme Powell, 25, was killed Aug. 19 after approaching St. Louis officers with a knife. Vonderrit Myers, 18, was fatally shot on Oct. 8 after allegedly shooting at a St. Louis officer.