Three persons were killed and one was seriously injured last night in a hit-and-run accident in which a van struck them as they were changing a tire on a car in McLean, a Fairfax County police spokesman said.

Police said they were searching for a white Chevrolet Nomad van with a right front headlight missing that struck the group about 10 p.m. and left the scene in the 1500 block of Westmoreland Street.

Police spokesman Warren Carmichael said the van's front end is likely to be damaged and blood is likely to be on the bumper.

The victims were not identified until relatives were told. Carmichael said they were apparently in their late teens or early twenties.

A man who was taken to Fairfax Hospital apparently suffered fractures of both legs. A fifth person escaped injury.

Those who were killed were thrown between 25 and 50 feet and pronounced dead at the scene.

A resident of Westmoreland Street who said she ran out of her house just after the accident said the group of people "in their early twenties" were "parked in a parking lane next to the curb. I know they were changing a tire."

Residents said Westmoreland is heavily traveled in morning and evening rush hours.

Willa Nabors, who has lived there since 1959, said accidents have been a problem on the street and that her husband suffered severe brain damage eight years ago when a driver lost control of his car and plowed through their front yard, just two doors from the scene of last night's accident.

"The car knocked down a telephone pole and my husband ran outside to see if he could help someone," Nabors said. "The pole and some electrical wires fell and struck him. He has never worked a day since.

"They have painted stripes in the road to direct traffic and it has helped a little," she said. "It's hard to believe that three people got killed in this one accident. I cannot bring myself to go outside tonight."