Police chief said officer who fatally shot black teenager had been in ‘imminent danger’ as series of surveillance videos that capture final moments released

St Louis police have released a series of surveillance videos that capture the moments before a black teenager was shot on Tuesday night in Berkeley, Missouri. Authorities insist the teenager, Antonio Martin, had pointed a handgun at the officer, who then killed him.

Two new videos were released on Wednesday that showed the immediate impact of the Berkeley shooting. One showed the officer, who remains unidentified, apparently being propelled backwards onto the ground by the force of his own gun, then turning, running and taking cover behind a gas pump.

Another newly released video, taken from the opposite angle, shows Martin and a friend walking up to the spot where the shooting happened. The camera fails to catch the shooting itself, but does show the friend running away from the scene very rapidly.

With darkness soon to fall in the St Louis suburb, local police chiefs and politicians are urging the community to remain calm, stressing that the circumstances of the death of Martin are different from the August police shooting of Michael Brown in Ferguson just a few miles away. Berkeley was disrupted by a protest in the immediate aftermath of Martin’s death that went into the early hours of Wednesday morning.

Jon Belmar, chief of the St Louis county police, released the first of the three videos at a morning press conference. It appeared to show Martin raising his hand straight in front of him in the direction of the police officer. Belmar alleged that the teen was holding a 9mm handgun loaded with six bullets. The police department released photographs of a black pistol later on Wednesday.

But Martin’s family expressed bewilderment and doubt about what had happened. His mother Toni Martin-Green told the St Louis Post-Dispatch, “This doesn’t make any sense for them to kill my son like this.”

Describing the sequence of events at a gas station in Berkeley, a suburb of St Louis, Belmar said that the officer had been in “imminent danger” and had used “what he felt was appropriate force at that time” by firing at the suspect across the hood of his patrol car.

He said the officer fired probably three shots, one of which hit the suspect, one the front tire of his vehicle. As he shot, he stumbled backwards and fell. The suspect, Belmar said, appeared not to have discharged the gun he was allegedly pointing.

An attorney for the police officer, Brian Millikan, confirmed that the officer was handed a body cam at the start of his shift but had been distracted and had not put it on. There was a second police recording device on the dashboard of his marked patrol vehicle, but that too was not turned on at the time of the shooting.

Belmar declined to identify the officer, who he said was a white male aged 34 who has been on the force for six years.

Martin’s death at about 11.15pm on Tuesday occurred just a few miles from Ferguson, where 18-year-old Michael Brown was shot and killed in August, sparking nationwide protests. The latest police shooting attracted a crowd of about 300 people to the Mobil gas station where Martin fell, and about 50 officers were called to the scene, some of whom used pepper spray on the people there. On this occasion, the Swat team was kept on standby and tear gas and flash bangs were not used – a conscious effort on the part of police, Belmar said, to learn from the lessons of Ferguson.

The police chief said that three “explosive devices” had been set off by individuals in the crowd. He described the devices as an “amalgam of fireworks that were packaged up and lit. It’s disturbing when it happens directly by a gas pump.”

Two officers were injured in the melee, he said, and there were four arrests.

The first video released by police shows two black teens standing in the parking lot of the gas station. One is dressed in a dark coat and pants, the other in a dark coat with white pants and a white hat.

As they walk away from the lot, a police car with its headlights on is seen driving into the parking lot and stopping in front of them. The officer gets out of the car just as the teen wearing the white pants comes up to him.

Belmar said the officer had been called following reports of a theft, though he declined to go into details.

The officer appears to engage the teen with the white pants in conversation, and as he does so the other teenager walks away but then returns and stands in front of the police vehicle’s headlights. At the end of the video, the teen with the dark pants appears to hold up his hand and point towards the officer just feet away.

Police say they recovered a gun they believed to be Martin’s at the scene. Belmar said the gun’s serial number was defaced, indicating it could have been stolen or contraband.

St Louis police will be hoping that the release of the video, and the evidence that they say shows that the officer was acting in self-defence at a moment of mortal danger, will defuse the anger that has erupted again in the city and avoid a repetition of the nightly protests that occurred in Ferguson.

Belmar said the suspect was “known to police” with an arrest record that included three assaults, armed robbery and unlawful use of a weapon. He added that police were keen to speak with the other person seen in the video, wearing white pants, who left the scene after the shooting.