Authorities in St. Louis are hunting for a gunman Tuesday who they say shot a police officer in what is believed to be an ambush attack.

The injured police officer -- identified as a 39-year-old sergeant with 16 years on the force -- was sitting inside his personal car in uniform when the shooting occurred. The officer's car was riddled with bullets and he was hit in the torso. He was saved by his ballistic vest, Fox2Now.com reported.

"They tried to assassinate a police officer," Sam Dotson, the city's police chief, told The St. Louis Post-Dispatch.

"They tried to assassinate a police officer"

- Sam Dotson, the city's police chief

Police in the city are searching for four African-American males in a gray Ford Taurus, the report said. One of the men may be injured.

The police officer was working his second job as a security guard. Police said he never got out of his car and had no interaction with the men.

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The Post-Dispatch reported that the Taurus pulled up in front of the sergeant's car at about 5 a.m. Tuesday and one of the assailants rushed out of the car wearing a black bandana on his face and opened fire.

The officer was reportedly able to return fire.

The officer was taken to Barnes Jewish Hospital with non-life threatening injuries. Authorities are reviewing surveillance cameras in the area.