St. Louis authorities say a man they believe was the getaway driver during an ambush shooting of a uniformed police sergeant has been charged with felony assault on a law enforcer.

Prosecutors also charged 27-year-old Edward Davis with armed criminal action in the pre-dawn shooting Tuesday that injured the officer while he sat in his personal car.

An 18-year-old suspect surrendered to police Wednesday and hasn't been charged. His attorney, Jermaine Wooten, says his client had no role in the shooting. Wooten says he anticipates also representing one of two other suspects who as of Thursday morning were at large.

The officer, a 16-year veteran of the department, was working security when a gunman masked by a bandanna opened fire.

The officer was treated at a hospital.