A 23-year-old woman was severely injured yesterday morning when she apparently lay down on the tracks at the Farragut North subway station and was struck by an oncoming Metrorail train.

The woman, who was trapped under the first car of the eight-car train for 45 minutes before rescue workers were able to free her, was identified as Gail Starken, of 13511 Keating St., Rockville. She was listed in critical condition with significant head injuries at George Washington University Hospital yesterday after having both feet amputated.

It was the first time since Metro opened 1 1/2 years ago in March 1976 that a person has been seriously injured during the course of normal subway operations.

Sheila Woody of Southeast, an eyewitness, told reporters that when she arrived at the subway platform moments before the incident occurred at 9:40 a.m., she saw a woman lying face-up on the train tracks. The woman had her legs across one rail, her head across the other and had both hands cupped over her face, Woody said.

"I screamed to the woman to get up. I told her the train was coming," said Woody, who said she was among two or three passengers waiting for the northbound Dupont Circle train. "But she didn't respond. She just laid there. When the train came in, I heard a 'thump' when it hit her."

Assistant Metro Police Chief Dennie Stewart said the operator of the train, Walter Williams, "observed what he perceived to be a white female who jumed on the tracks" as Williams' train approached the station.

Stewart said Williams attempted to make an emergency stop by pressing the "mushroom button," a device in the train designed to bring the vehicle to the quickest stop possible. But Williams was not able to stop the train before it struck the victim, officials said.

A Metro spokesman said Williams was being placed on administrative leave for the remainder of the work day, which is standard procedure in such incidents, according to the spokesman.

The station operator at Farragut North was told by a passenger about the presence of the woman on the tracks just seconds before the train pulled into the station. "The station operator called central control and asked them to cut the electricity to the train, but the call was too late," the Metro spokesman said.

Officials said there was no major disruption of train service during the accident. Trains were put back on schedule a short time after the incidently routing them onto an adjacent track.

There was no immediate explanation for the apparent suicide attempt, according to Metro officials.