KITTRELL, N.C. _ Investigators say they have no idea why twin 11-year-old boys allegedly opened fire in their family's home, killing their father and wounding their mother and sister.

The twins, whose names were not released, were each charged Friday with murder and two counts of assault with a deadly weapon after the incident the night before.

``Both were equally responsible. Both were equally involved,'' said sheriff's Capt. John C. Shockley.

William Harvey Bawcum Jr., 46, heard the sound of bullets and bounded up the staircase to protect his wife, Shockley said. He was shot in the right cheek and throat and died at the scene.

Sixteen-year-old Robin Bawcum was hit below her right collarbone. Her mother, Deborah, 45, was wounded in her right arm.

Robin Bawcum was in fair condition and Mrs. Bawcum was in good condition at Duke University Medical Center late Friday.

Authorities say after the shootings, the boys waited for officers to arrive. Police were unsure who called 911.

``It was a terrible, bloody mess. There was a lot of blood all through the house,'' Shockley said.

Investigators said they recovered a .32-caliber handgun.

The sheriff's department had no record of being called to the home 35 miles north of Raleigh for domestic disputes, but Shockley said after talking to Mrs. Bawcum, investigators ``understand they've had problems with school.''

Neighbors said Bawcum, a technician for the local telephone company, was an avid hunter and fishermen, and the boys practiced with BB guns on the family's thickly wooded lot.

``That's where they learned to use guns,'' said Darlynn Oxendine, a family friend and a physical education teacher who was Robin's basketball and volleyball coach.

Oxendine, who spent hours consoling Deborah and Robin Bawcum at the hospital, said Mrs. Bawcum kept saying, ```He came up to save me.'''

Oxendine said she was shocked by the shootings.

``All little boys are mischievous. But these boys you'd never imagine would shoot somebody,'' she said.

A juvenile court hearing is scheduled next Wednesday. The boys were being held Friday in separate juvenile centers.