LIVERMORE — A teenage girl from Jay was critically injured Friday morning when her car crossed the centerline on Route 4 and collided head-on with a pickup truck.

Lauren Faeth, 17, was being treated Friday night at Central Maine Medical Center in Lewiston. Police described her injuries as critical.

The vehicles collided at about 9:45 a.m. near Round and Long ponds, forcing the closure of a portion of Route 4 while police reconstructed the scene.

Investigators from the Androscoggin County Sheriff’s Department said Faeth was driving south when her 2001 Saturn drifted across the centerline. It collided with a Toyota Tacoma driven by Jeffrey Hartford, 45, who was headed north in the pickup owned by Radio Communication Management of Portland, police said.

Hartford and a passenger, Shawn Jordan, 32, of South Portland, suffered less severe injuries. They were treated at the Lewiston hospital and released.

Route 4 was closed at the intersection with Crash Road and at the intersection with Route 108. Vehicles traveling north were sent across Route 108 to Norlands Living History Center and up Gibbs Mill Road back to Route 4, Livermore fire Chief Donald Castonguay said.

Gary Desjardins was visiting a home near the scene of the crash when he and other neighbors heard tires screeching and a loud crash. He went to slow traffic on the busy highway while another driver went to check on the occupants of the vehicles, he said.

Firefighters cut the doors and roof off the Saturn to free Faeth, he said.

The crash was being reconstructed as the Sheriff’s Department continued to investigate. It was not immediately clear what caused Faeth’s car to drift into oncoming traffic, police said Friday night.