The woman who abandoned an infant girl Tuesday at the Rosslyn Metro station has been found, and the child has been temporarily placed in foster care, officials said yesterday.

Employees at Alexandria Hospital, hearing descriptions in the media of what the woman was wearing, provided clues that led Metro police to the mother, officials said. The woman, who lives in Fairfax County, had gone to the hospital seeking treatment for the baby that day, they said.

The mother has acknowledged that the baby is hers, and Metro police were trying yesterday to establish positive identification through footprints, according to Paulette Jackson, supervisor for the Pro-Child Unit at Arlington's Department of Human Services. The woman's name has been withheld.

The baby, between 6 and 12 weeks old, "appeared to be well cared for," Jackson said. The child was placed in foster care after a hearing Wednesday in Arlington juvenile court, and social service officials will seek a second, expedited hearing to resolve the baby's future, she said.

Metro police are working with social services to ensure that the baby will be safe if returned to her mother, said Metro spokeswoman Beverly Silverberg. Whether criminal charges will be sought has not been decided, she said.

"We're looking for ways to make sure the baby is in a safe environment," said Silverberg.

The incident occurred at the base of an escalator about 2 p.m., when a woman who appeared to be in her thirties approached another woman, handed her the infant and asked her to "hold my baby," Silverberg said. The woman then vanished up the escalator, officials said.