Police are looking to interview four survivors of a weekend car crash that killed a 19-year-old Ivyland man to help determine the cause of the accident, Northampton Township Chief Barry Pilla said Monday.

"We haven't talked to them, because of their injuries," Pilla said. "They were just a bunch of guys who went out for pizza."

Killed in the crash Saturday was Cameron Smithwick, 19, a passenger in the white Chevrolet Monte Carlo SS, Pilla said.

Death was caused by multiple injuries, Bucks County Coroner Joseph Campbell said Monday. Smithwick suffered severe head trauma and multiple fractures, and was pronounced dead at the scene.

"This is every parent's nightmare," Campbell said, "I have three teenagers myself."

Injured were Monroe Leonard Tanner IV, 18, of Ivyland, and Louis Piotti, 17; Matthew Slade, 18; and Daniel Harris, 17, all of Holland, police said.

Piotti, Slade, and Harris had been discharged from St. Mary Medical Center by Monday morning, a hospital spokeswoman said. There was no information about Tanner, she said.

Tanner may have been the driver and Smithwick may have been a passenger in the front seat, Pilla said.

The teens were heading home at 1:50 p.m. when the car ran off Old Jacksonville Road, a two-lane stretch between Ridge Way and Sackettsford Road, police said. The car hit a utility pole and then a tree.

The car was so mangled that Pilla could not identify the make from a photo.

"It's a wonder that any of them were able to get out of it," he said.

Firefighters had to cut off the roof and a door to get the driver out.

Authorities could not say whether any of the teens were wearing seat belts.

Officer Joseph Rosowski, an accident-reconstruction expert, was investigating the crash. Police asked anyone with information about the crash to call him at 215-322-6111.

At Council Rock North and South High Schools, counselors were available to help students deal with the accident, according to a statement from Superintendent Mark Klein. It was not clear whether the men were students or recent graduates.

The police chief called the accident "a horrible tragedy."

"Right before the holidays," such a loss is especially hard to deal with, he said.

Contact Bill Reed at 215-801-2964, wreed@philly.com, or follow @breedbucks on Twitter. Read his blog, "BucksInq," at www.philly.com/bucksinq.