Two 18-year-old Oil City men traveling to Pittsburgh to enlist in the Army were killed Wednesday morning when a tractor-trailer flipped on top of the car in which they were riding on Interstate 80, authorities said.

The crash happened at about 5:30 a.m. in the westbound lane of I-80 in Findley Township, state police said.

Police said Brad A. Knight and Daniel R. Daubenspeck were being driven to Pittsburgh by a recruiter when the car spun out of control on icy roads. The car slid into a tractor-trailer that had jackknifed ahead of it. The rig continued to slide, forcing two other vehicles in front of it into another tractor-trailer that also had jackknifed.

Knight, who was a front-seat passenger, and Daubenspeck, who was in the back seat, were pronounced dead at the scene at 6:45 a.m. by Mercer County Deputy Coroner Scott A. Black, who ruled the deaths accidental. He said the two died of head injuries.

Recruiter Laurence G. Stein, 29, of Russell, Warren County, was treated at United Community Hospital, Pine Township, a hospital spokeswoman said.

According to a UCH spokesperson, Jose Samano-Amezcua, 24, and Manual Coyt, 26, both of Portchester, N.Y., were taken to Allegheny General Hospital in Pittsburgh. However a spokesperson at Allegheny General said there had no record of the men. Samano-Amezcua was driving a sport utility vehicle, police said; Coyt was a passenger in the SUV.

Kathleen Currier, 45, of Youngstown, who was driving the tractor-trailer, also was treated at UCH, the spokeswoman said.

The fourth vehicle was a car driven by Pedro Daley, 25, of Bronx, N.Y., police said, adding he had two passengers.

State police closed both westbound lanes of I-80 from 9 to 11 a.m. to clear the wreckage.