Park City, UT : Three people injured in single-vehicle crash in Parleys Canyon on Thursday December 31 2015.

Westbound I-80 traffic was shut down at the mouth of Parleys Canyon on Thursday after three crashes in the area, including one involving a police car.
A Park City police officer was responding to a single-vehicle wreck and attempting to establish traffic control when another vehicle tried to avoid the police car and struck a semitrailer, the Utah Highway Patrol said.
A following vehicle was unable to avoid the police car, according to the agency. The officer was not inside the police car at the time and was not injured. Three others were taken to nearby hospitals with injuries that were not life-threatening.

Source:
Police car hit in one of three I-80 crashes that close freeway, injure three