Three children, ages 7 to 13, and an adult companion who had waded into a farm pond in rural Fauquier County, Va., yesterday became mired in deep mud and sank to their deaths as another child tried to rescue them with a stick, then rode his bike to seek help.

Fauquier Sheriff Joe Higgs said none of the four could swim. He said the incident began as a bike outing when Zavis Hill, the 27-year-old boyfriend of the woman who was baby-sitting for the children at her home in Ashville, Va., about 50 miles west of Washington, took all four for a bike ride.

They stopped at the man-made, kidney-shaped pond on a farm that is for sale in Rectortown, about three miles away, Higgs said. The pond is normally six to eight feet deep, he said, but recent heavy rains added 12 to 14 inches of silt to the bottom.

Hill waded into the pond along with April Williams, 13, her brother, George Hamm, 8, and their cousin, Tina Hamm, 7, while Tina's brother, Jerry, 10, remained near the pond's edge, Higgs said.

The fresh mud acted like quicksand, the sheriff said, sucking the four swimmers toward the bottom as they thrashed around trying to save themselves. "They were in over their heads, they panicked, and the silt pulled them under," he said. "It happened in a matter of minutes."

Jerry Hamm first tried to rescue the others by throwing them a large stick, then bicycled back to the home of the babysitter, Estelle Thompson, a trip over hilly terrain that Higgs said probably took half an hour. Authorities were called at 11:30 a.m., and by the time rescuers arrived at the pond, the bodies had been in the water about 45 minutes, Higgs estimated.

Assistant Fire Chief Randy Emory, of the Marshall Volunteer Fire Department, was the first person to arrive at the pond. He pulled the four out and started cardiopulmonary resuscitation, but it was obvious that it was too late, Higgs said. All were pronounced dead of drowning at Fauquier County Hospital.

Rescue personnel from the Warrenton, Middleburg and The Plains fire departments also responded to the scene.

"This is the first time in the history of this county that we lost three children in one incident," Higgs said. "We normally have one or two drownings a year in these ponds."

Higgs said that ponds are popular swimming spots for area children and that the county has hundreds of them. "It is the country way," he said. "These children are raised this way.

"As parents, we worry about alcohol, drugs and firearms," he said. "But sometimes we forget the obvious."