WHEELING, W.Va. (AP) _ A riverboat pilot went on a killing spree hours after checking out of a mental health clinic, shooting his wife and two daughters, then driving across town to kill his brother and mother before committing suicide, police said today.

All six died from gunshots to the head.

Mark Storm, 30, ``seemed to be stressed out and quiet'' at a birthday party before the shootings Thursday night, said James Gallaher, a neighbor and the host of the party.

``We're grieving. They're our good buddies,'' Gallaher said this morning.

Police believe that Storm, who was on leave from his job, used a 9mm semiautomatic pistol to shoot his wife, Betty, 26, then killed his daughters _ Jessica, 8, and Megan, 3 _ as they lay in their bunk beds.

He then drove about 2 1/2 miles to his brother's house, where he shot Benjamin Storm, 32, and their 59-year-old mother, Roberta Nyles, Police Chief Ed Long said.

He shot himself outside his brother's home on an island in the Ohio River about 50 miles southwest of Pittsburgh. Police pulled Storm's body from the water at the same spot he fished at as a child, friends said.

``It looks like he was intent on killing himself. The last bullet was the one he used on himself,'' Long said. The weapon was bought last June at a local gun shop.

Police had no motive for the shootings.

Storm checked into the adult psychiatric wing of Ohio Valley Medical Center on Sunday, said James Stultz, senior vice president of human resources for the hospital's parent company, Ohio Valley Health Services and Education Corp.

The hospital would not say why he admitted himself, citing doctor-patient confidentiality. Long said Storm suffered from stress.

Storm left the hospital Thursday morning with his doctor's permission. He returned with his wife two hours later to meet with the doctor and make arrangements for a return visit. He also was given a prescription, Stultz said.

Storm, who was in a continuous-care wing that handled a variety of psychiatric patents, would not have been allowed to leave if he was deemed to be a danger to himself or anyone else, Stultz said.

``This is certainly not anything that anyone anticipated. It's just a complete shock to us,'' Stultz said.

Storm, his wife and daughters attended the party until about 7:40 p.m. After the family went home, Gallaher noticed Storm's car was no longer parked in front of the house.

``He tried to call the Storm house and got no answer,'' said Lt. Michael Whalen. ``So, he walked over to check the house, and when he opened the front door, he saw Betty Storm lying on the living room floor in a pool of blood.''

When Gallaher called police around 9:30 p.m., they were already responding to a call at Benjamin Storm's home on Wheeling Island.

Jeanine Wiselka, a neighbor of Benjamin Storm's, said his girlfriend ran from the house yelling for someone to call police and then said ``He's got a gun!''

Wiselka said she then heard two shots being fired in the home.

Police found Benjamin Storm's body on the floor. Mrs. Nyles, who used a wheelchair, was found in an upstairs bedroom and taken to a hospital, where she later died.

At the top of the front steps to the tan, 2 1/2-story Victorian home, a piece of paper taped to the wood railing read, ``Go Away.''

Christy Gongola, who lives three houses from Mark Storm, learned of the shootings early today as she prepared to leave for work.

``Oh wow! That's just sad,'' she said. ``You hate to hear that, especially the little girls.''