A man trying to cross a Fairfax County road at one of the Washington area's most dangerous intersections was struck by a car and killed last night, county police said.

The man, who was not identified immediately, was hit about 6 p.m. in the westbound lanes of Route 50, at Patrick Henry Drive in the Seven Corners area.

Police said the man was struck just west of the intersection, apparently after slipping and falling. One or more vehicles swerved around him, and it was not clear whether the driver who struck him was aware of what happened, a police spokeswoman said. The vehicle was not located.

Officer Beth Funston described the victim as Hispanic, in his mid-50s, with thinning hair. He wore a black jacket, flannel shirt and dark pants and shoes. She asked for help from the public in identifying him.

Three years ago, it was reported that a pedestrian was hit in that immediate area every three or four months.

Moreover, a study in 2003 found that more pedestrians had been struck at Route 50 and Patrick Henry Drive than at any other intersection in the county. Between 1995 and 2001, according to the study, 22 pedestrians were killed or injured there. That was two more than the second-most-dangerous spot, also on Route 50 but farther west, at Graham Road.

Authorities have said many of the Seven Corners incidents area involved residents of the largely immigrant neighborhoods in the Route 50 corridor.

Traffic is heavy on Route 50, the road is wide and distances between traffic signals are long. Intervals between "walk" signals also might seem long in the area, where people often run to catch a bus. It was not clear if ice played any role last night.