A state trooper is expected to be released from Harborview today after his patrol car was hit on I-5 late Monday night.

Just before 11 p.m., Trooper Chris Caiola was parked on the right shoulder of southbound I-5 near 196th after he had finished with a violator. His cruiser was suddenly struck from behind by a car driven by a 19-year-old Everett woman.

Medics had to extricate Trooper Caiola from the wreckage. His drug-sniffing dog Buster was also in the car. He was shaken up but not injured.

The woman and her three passengers were not seriously hurt. Alcohol or drugs are possible contributing factors in the crash. The driver was booked into the Snohomish County Jail for DUI.

“Unfortunately this shows how dangerous our job is,” Trooper Keith Leary said. “This could have turned out a lot worse.”

The southbound lanes were closed for about 3 1/2 hours while troopers investigated the crash.