OXFORD — An Auburn motorcyclist remained in critical condition at a Lewiston hospital Thursday night with head injuries suffered when he collided with a pickup truck leaving Oxford Plains Speedway on Wednesday.

Richard Lothrop, 58, of 6 Russell Ave. was being treated for a brain stem injury and fractured skull, Oxford County sheriff’s deputy Josh Wyman said Thursday night. A nursing supervisor said Lothrop was in critical condition.

The truck was driven by the 17-year-old daughter of David Brown of Poland, Wyman said.

Both David and his daughter Kristen are racers at the stock car racetrack on Route 26, an official said.

Wyman said the accident occurred about 8:30 p.m. as the Browns were following each other out of the parking lot to head south on Route 26. Both were driving pickups registered to him and each was hauling their race car behind.

The investigator said as Lothrop drove south on the highway, the teenager pulled out ahead of her father to go south and didn’t see the motorcycle.

“Richard locks up his brakes, starts fishtailing. She sees the motorcycle fishtailing and he dumps the bike right there. He wasn’t wearing a helmet,” Wyman said.

Neither driver had passengers, he said.

No charges have been brought, he said, and the accident report will be turned over to the District Attorney for review. Wyman said there is no indication at this time that speed or alcohol were involved.

“She has quite a bit of experience driving the truck. She actually does race at the speedway,” Wyman said.

Lothrop’s 1996 Royal Star Yamaha was registered to him.

The deputy was assisted by Oxford police Sgt. Rickie Jack and Lt. Mike Ward, and sheriff’s Cpl. Justin Brown, who is doing a reconstruction of the accident. Oxford Fire and Oxford Rescue also assisted at the scene.