A driver suspected of being on drugs hit two Colorado State Patrol vehicles investigating a crash on Interstate 76 Saturday night.
A Chevrolet truck hit a CSP Ford Crown Victoria, pushing it into a CSP Dodge Charger, investigators said.
It happened just before 9 p.m., while troopers were investigating a crash on the ramp to Interstate 76 from northbound Interstate 25.
The troopers' vehicles were positioned blocking the left lane of the exit ramp and had their emergency lights activated, according to the CSP.
The troopers were not in their vehicles at the time of the crash and no one was hurt.
The driver of the truck, Keith Kilbey, 23, from Arvada, was arrested and charged with driving under the influence of drugs.
"We believe marijuana," CSP spokeswoman Cpl. Heather Cobler told The Denver Post on Sunday.
"It is unacceptable that troopers and their vehicles continue to be hit on our roadways." said Corporal H. Cobler. "This time we were fortunate, but many officers across the nation are not so lucky."
Colorado law requires drivers to move over or slow down when approaching a stationary emergency vehicle that has its emergency lights activated..