St. Louis' police chief is crediting a bullet-resistant vest for saving a sergeant he says was ambushed and shot while sitting in his own car working a second job.

Police Chief Sam Dotson says the injuries sustained by the 39-year-old officer before dawn Tuesday were not considered life-threatening.

Dotson says the gunman or shooters "tried to assassinate a police officer."

Dotson says the 39-year-old officer was in full uniform when a car pulled up in front of his. A passenger wearing a bandanna covering his face got out and opened fire on the officer, who returned fire and believes he hit at least one of the suspects before they sped away.

There was no immediate word about any arrests.