DOTSERO, Colo. -

The Colorado State Patrol says a trooper wounded in a shooting during a traffic stop on Interstate 70 in western Colorado is in critical condition and a motorist he was trying to help was shot and killed.

Garfield County Sheriff Lou Vallario said the shooting happened Thursday in Glenwood Canyon when a motorist suddenly opened fire. The sheriff says another trooper returned fire and killed the suspect.
    
Vallario says investigators are still trying to identify the suspect and determine a motive. He says there are no other suspects.
    
Authorities say the injured trooper, identified as 31-year-old Eugene Hofacker of Vail-Avon, suffered serious blood loss and underwent surgery.
    
Interstate 70 was closed for hours, and was expected to reopen in both directions Thursday evening.