A Woodbury police officer was hospitalized with serious injuries Friday after a tow truck rear-ended his squad car on Interstate 494 at Tamarack Road.

Officer Bryan Wagner, 30, was parked on the median of northbound 494 when a tow truck slammed into him from behind around 2 a.m. Friday It remains unclear what caused the driver to veer off the roadway, said police spokeswoman Michelle Okada.

Wagner was taken to Regions Hospital in St. Paul with “significant injuries,” but is expected to survive. Woodbury police released pictures of his mangled squad car, its back end crushed like an accordion.

Wagner has served as a Woodbury officer for four years.

The tow truck driver, identified as Joshua Barnhill, 45, of Oakdale, Minn., also suffered minor injuries.

Both men were wearing their seat belts. An initial investigation by the State Patrol determined that alcohol was not a factor in the crash.