A Los Angeles police officer was in serious condition Tuesday after he was struck by a vehicle while conducting a traffic stop on the northbound 405 Freeway in the West Los Angeles area.

The officer was conducting a traffic stop on the freeway when he was struck by another vehicle, the Los Angeles Police Department tweeted.

The officer suffered a serious leg injury, but was expected to survive, Police Department Officer Mota told KTLA.

The driver of the vehicle that struck the officer was arrested after officers administered a field sobriety test, ABC 7 reports.