High school students on their way to a band competition at the Jersey Shore were jolted awake early yesterday when their charter bus plowed into a tractor-trailer on the Pennsylvania Turnpike in Chester County. The crash critically injured the bus driver, but most passengers had only scrapes, bumps or a bloody nose.

The bus, which was taking students and chaperones from Elizabeth Forward High School outside Pittsburgh to the Tournament of Bands Weekend in Wildwood, ran into the rear of the tractor-trailer shortly after 4:30 a.m. in Wallace Township, state police said.

Dozens of students were slightly injured, and one had a broken arm.

The tractor-trailer had been parked in a pull-off area and was pulling back onto the turnpike at 40 m.p.h. when hit by the bus, which was going 60, police said.

Upon impact, the vehicles traveled 400 feet together before stopping in the right lane.

The front of the bus was obliterated, according to video shot from a TV news helicopter.

The bus driver, Timothy Berkshire, 49, of Masontown, Pa., was flown to Lancaster General Hospital in critical condition.

The trucker, Willie Ruff, 58, of Brownsville, Pa., was not injured.

State police had not determined whether either driver would be cited.

The turnpike was closed for hours in both directions so emergency vehicles could arrive and helicopters could land.

After receiving treatment, students spent the day expressing concern about the bus driver, taking hospital tours, dozing, and fighting off boredom while they waited for parents or a second bus from T.A. Nelson Bus Lines to pick them up.

"You know it's a bad day for a high school kid when they're sitting there and they say, 'Boy, I wish I was in chemistry class,' " said Mike Jupina, a spokesman for St. Joseph Medical Center in Reading, which treated and discharged 12 students and three adults.

The bus, which had left the Pittsburgh suburb of Elizabeth shortly after midnight, was about 270 miles into its 385-mile trip when it crashed.

It carried 29 students, band director David Cornelius, three other staff members, and seven parents.

The tournament was to start last night and run through Sunday.

Everyone on the trip - except Cornelius, who was expected to be released from a hospital today - was headed home by late yesterday afternoon, school district spokeswoman Jane Milner said.