A 21-month-old baby and his 14-year-old baby sitter disappeared late Sunday or early Monday from a town house apartment in the Waldorf, Md., area, Charles County sheriff's deputies reported yesterday.

However, deputies said there are no signs of foul play and they believe that the baby sitter, who has often run away from home, may have taken the baby.

"We're concerned for the well-being of both of them," Sgt. Casey McDevitt said. "We're obviously looking for the girl to return the baby."

McDevitt said that Tammy Lynn Giles began baby-sitting Friday for Michael Justin Fitzgibbon at the Fitzgibbon home at the request of the baby's 15-year-old sister. The mother, Sharon Fitzgibbon, was away for the weekend, McDevitt said.

"As of 11 o'clock Sunday night, everything was normal," he said, "but when the mother returned Monday morning, both the baby sitter and the baby were gone."

McDevitt said there was no sign of a struggle in the house. He said that in the past two years, Tammy has been reported by her parents as a runaway about 20 times.

"They have no money and no car," McDevitt said. "We have no idea . . . how they got away."

Tammy has blond hair and blue eyes, is 5 foot 2 and weighs 120 pounds.

The baby, last seen wearing a blue and white sunsuit, has light brown hair and brown eyes.