A Virginia woman was killed yesterday when she apparently stepped into the path of an Amtrak passenger train at the same Montgomery County railroad crossing where a mother and child were killed in a murder-suicide last month, police said.

The woman--identified only as 40 years old and from Vienna--was struck by the Capitol Limited at 3:45 p.m. at a gated crossing at Randolph Road and Nebel Street in Rockville, said Montgomery police spokeswoman Joyce Barrow.

None of the 226 passengers on the train, which left Chicago at 8:05 p.m. Thursday, was injured, an Amtrak spokesman said.

The incident yesterday occurred at the start of the afternoon rush hour, backing up Amtrak, MARC and freight trains and sending thousands of rail commuters scrambling for alternate ways home. Traffic on Rockville Pike and Montrose Road slowed to a crawl, and Randolph Road was closed between Rockville Pike and Parklawn Drive for several hours.

The tracks from Silver Spring to Rockville remained closed as of 7 p.m., authorities said. Metro trains were not affected because the tracks run underground in the Randolph Road area.

Witnesses told police they saw the woman already within the gates that had lowered. The woman appeared to be looking through binoculars or a camera toward the approaching train before she knelt in front of it, witnesses told investigators.

Parts of her body were scattered about one-tenth of a mile south of the intersection. Police covered them with white cloth and marked them with yellow numbers. The remains were taken to the Baltimore Medical Examiner's office, where they were to be positively identified using dental records. The woman's white, four-door Volvo S70 sedan with Virginia plates was parked in a nearby parking lot, police said.

A team of crisis counselors arrived with police and CSX officials to meet with Amtrak employees on the train and motorists and pedestrians who saw the incident, police said.

About 1,800 passengers on the MARC Brunswick line were told at Union Station and at stops along the Metro Red Line that they should take Metro to the Rockville stop. From there, they could catch a westbound MARC train or buses to other MARC stops, said Frank Fulton, a spokesman for the Mass Transit Administration, which operates the MARC system.

The Amtrak train, which was already running an hour late, sat on the tracks while police investigated, said Amtrak spokesman Derrick James. The train was expected to continue on to Union Station after the tracks reopened.

Yesterday's apparent suicide was the third at that crossing in three years. The most recent, involving 23-year-old Maribel Gonzales and her 2-year-old daughter, Pamela Arumada, was June 6. In 1996, a 24-year-old man walked onto the tracks as a MARC train approached him.