A white police officer who fatally shot a black teenager at a gas station in the city next door to Ferguson, Mo., on Tuesday evening has sparked violent clashes between demonstrators and law enforcement, with protestors reportedly carrying bags of rocks, smashing police cars, and hurling explosives and bricks.

The unidentified officer, a 6-year veteran of the department, reportedly "feared for his life" when the 18-year-old pointed a gun at him in the city of Berkeley, the mayor said on Wednesday morning after analyzing a video of the confrontation. A handgun was later recovered from the scene, New York Daily News reported.

"This was not the same as Ferguson," Mayor Theodore Hoskins said, adding that the police officer was probably attempting to save his own life while responding to a shoplifting report.

However, Martin's mother, Toni, told NBC affiliate KSDK that the 18-year-old had been on his way to meet his girlfriend when the fatal encounter happened and that he was not carrying a gun. "He only just left the house to go see her," she said.

"They got my baby laying out there. He's been out there for about two hours," she said.

Following Tuesday's incident, "between 200 and 300 protesters gathered at the scene after the shooting, and conflicts broke out between officers and protesters" in Berkeley, which is two miles from Ferguson, according to St. Louis Post-Dispatch.

Four people were arrested for assaulting officers, and at least one officer was injured when he tried to get away from some sort of firework device set off in the parking lot, St. Louis County Police Chief Jon Belmar said.

While one police officer was taken to the hospital with leg wounds after being injured while attempting to flee from an explosive device, another officer was hit in the face with a brick.

Additionally, a fire was reportedly started at a QuikTrip across the street from the crime scene and several police cars were damaged.

"I can see about 50 cop cars," said Bradley Rayford, a photographer at the scene. "They're fighting and scuffling, the highway is blocked with cars, people are being arrested. Trash cans are on fire."

The shooting cannot be compared to the police killing of Michael Brown in Ferguson or to the chokehold death of Eric Garner in New York, Hoskins stressed, pointing out that the Berkeley police department is majority-black.

"Everybody don't die the same," the mayor told reporters. "Some people die because the policeman initiated. Some people die because they initiated it. And at this point, our review indicates that the police did not initiate this, like Ferguson."

"These are nothing but tragedies," Belmar said as he offered his condolences to the victim's family. The officer "will have to carry the weight of this for the rest of his life," he said, adding that the officer had been placed on administrative leave.

Meanwhile, Hoskins promised a thorough investigation but said that the video showed it was not a police officer going off "half-cocked," acccording to Star Tribune.