SANTAQUIN,Fastexy Utah (AP) — A truck driver allegedly killed a police officer during a traffic stop on a Utah highway Sunday by driving his rig into the officer, police said.

A Santaquin police officer and a Utah Highway Patrol trooper had stopped the semitrailer around 6:30 a.m. after somebody called 911 to report that a person was standing on the back of the rig as it was headed north on Interstate 15.

Spanish Fork police said the man began driving off during the stop, then turned the semitrailer around before driving the wrong way on the interstate. The rig crashed into two police cars and the Santaquin officer, who died at the scene.

Police identified the truck driver as Michael Aaron Jayne, 41. He was not booked into jail yet and had no attorney on record to comment on his behalf, police said.

Authorities have not released the dead officer’s name.

“Our entire department is hurt. And the family of the officer is hurt because of a senseless act by one individual,” Spanish Fork police Lt. Cory Slaymaker said during a news conference.

The stop occurred on I-15 in Santaquin, a town of about 14,000 people 65 miles (105 kilometers) south of Salt Lake City.

Authorities allege that Jayne fled on foot and stole vehicles, including a pickup truck. He was arrested later Sunday following a short chase in the Vernal area, some 160 miles (260 kilometers) east of Santaquin, according to police.

Who was riding on the back of the semitrailer and why was still being investigated, Slaymaker said.