A woman was shot to death and her husband was critically wounded yesterday by shotgun blasts at their home west of Leesburg. Their son was arrested and charged with murder, the Loudoun County Sheriff's Office said.

Joshua E. Tulip, 18, who lived with his parents in the rural Neersville area, was arrested in Purcellville shortly after the shooting, authorities said, and charged with first-degree murder.

Investigators said last night they did not know of a motive for the shootings.

Barbara Tulip, 48, was found dead in the single-family house on Route 687, a gravel road west of Route 671 about 15 miles from Leesburg, said sheriff's deputy Carol Showalter.

David E. Tulip, 52, was reported in critical condition last night at Washington Hospital Center, where he was taken by helicopter.

According to a friend, Barbara Tulip was involved for years in civic activities, including the Community Association of Hillsboro and 4-H Clubs. "She was a wonderful lady," said the friend, who asked not to be named. "It is a terrible tragedy for our community."

The slaying was the first of the year in Loudoun County. There was only one slaying in the county last year -- a fatal stabbing in September -- and that was the first since 1985.