An Amtrak Acela train hit and killed three teen-agers trespassing on railroad tracks in suburban Philadelphia on Sunday, authorities said. None of the roughly 300 passengers were hurt.

The three were among a group of five teen-agers on the tracks, Falls Township Police Officer Harvey Taylor said.

A 14-year-old boy, a 15-year-old boy and a 19-year-old man were killed, acting Police Chief Neil Harkins said. A 14-year-old girl and a 14-year-old boy got away before the train reached the group.

The victims were not immediately identified. Taylor described them as juveniles from the area.

The crash happened at about 3:45 p.m. in Morrisville, about 25 miles northeast of Philadelphia, Amtrak spokeswoman Karen Dunn said.

"We're not sure what the circumstances were yet. I haven't gotten a report from the engineer," Dunn said.

Acela trains can go up to 150 miles per hour, but Dunn did not know what the speed limit at the time of the accident. Engineers need at least a mile to stop a fast-moving train if they see someone on the tracks, Dunn said.

"I just don't know how much notice he or she had," she said. "It's tragic for the engineer, because in cases like this you can often see it but not prevent it."

Passengers on the southbound Acela train en route to Washington, D.C., remained on the scene hours after the accident waiting for another train to pick them up.

Service on other Amtrak trains was restored within 30 minutes, Dunn said.

The Acela Express is a high-speed service between Washington and Boston.

It is the second fatality involving an Acela train. In September, a 71-year-old Warwick, R.I., man was killed by an Acela train while walking on railroad tracks near his home.