Moments before an unmarked police car hits man who jumped out of another vehicle.
CNN  — 

A fired police officer in suburban St. Louis was charged with assault, a day after video was released showing his unmarked SUV striking a man and the officer getting out of the vehicle and kicking him, a prosecutor said.

Joshua Smith, who worked for the Florissant, Missouri, Police Department, faces first- and fourth-degree assault charges and armed criminal action, St. Charles County Prosecuting Attorney Tim Lohmar said Wednesday.

The charges were filed after a review of footage from a resident’s surveillance camera recorded on June 2, prosecutors said. Smith was fired June 10.

“The moment that vehicle turned its headlights towards the victim, that became a 4,000 pound-missile,” Lohmar told reporters.

Smith’s attorney, Scott Rosenblum, told CNN the video is a small part of the encounter “and fails to tell the entire story” of the incident, which he called an accident “under extraordinary circumstances.”

The officer was involved in a pursuit of a vehicle.

“We have a situation where the driver, after taking off, jumped from a moving vehicle – allowing the vehicle to continue unoccupied,” Rosenblum wrote in an email. “Unexpectedly the injured individual also jumped from the car. Mr Smith never intended to hit him. Nor expected another occupant to jump in front of him from a moving car.”

Video from the scene shows the man being hit as he runs from a car as it slowly rolls down a street.

The fourth-degree assault stems from the former officer kicking the victim while he was on the ground, already suffering from a broken ankle, Lohmar said.

A probable cause statement says Smith also struck the man before putting him in handcuffs.

“It was shocking, to say the least,” Lohmar said of the video.

Jerryl Christmas, an attorney for the unidentified injured man, told CNN affiliate KMOV that his client “suffered serious injuries requiring surgery and remains traumatized by this shocking incident.”

Smith, who had been with Florissant police for nine years before he was fired last week after the release of a prior video, had been on security detail because of “hints of looting and vandalism” after anti-racism protests in the area, Lohmar said.

Smith, 31, and two other police officers in the SUV were following a car that matched a description of a car involved in a “shots fired” incident from days earlier, Lohmar said.

The car didn’t immediately pull over when Smith turned on the unmarked Ford Explorer’s siren and lights, officials said. Eventually, it came to a stop in a residential neighborhood, as the occupants got out and ran, Lohmar said. The victim was one of those three, according to Lohmar, he said.

Florissant is north of St. Louis and close to Ferguson, where 18-year-old Michael Brown was killed in a confrontation with police in 2014 that gave impetus to the Black Lives Matter movement.

CNN’s Gregory Lemos contributed to this report.