An automobile mechanic shot and killed his girlfriend, shot his 11-month-old daughter "between the eyes" and then killed himself early today at a Baltimore-Washington International Airport service station, according to police and the man who identified the bodies.

State Police said that moments before the killings and suicide, Charles Perry Black, 25, of Baltimore, shot a coworker at the station twice and wounded him. The coworker, David W. Pease, 29, is in good condition at the University of Maryland's shock trauma unit in Baltimore.

According to police, Black drove to an airport service station just after midnight with his girlfriend and baby, went inside and took his pistol from a toolbox.

In the station, Black shot Pease, and then ran to his vehicle which was parked nearby, killed the woman and the baby and then shot himself fatally in the mouth.

"From what we've been able determine from family members and friends, he was depressed," said State Police spokesman Dan McCarthy. "He and the girlfriend were separated and they apparently had some domestic troubles."

Slain were Joleen J. Beaty, 22, of Savage, Md., and the couple's infant daughter, Stephanie Black.

Pease, who lives in Harmans, Md., was rushed by helicopter to the shock-trauma unit with wounds to the left elbow and shoulder.

"I can't tell what problems he might have had, but the baby had to be innocent," said Sgt. W.E. Jones of the State Police BWI Airport Division.

Robert Atwood, owner of the service station, said Black had worked for him for 15 months and was a "good mechanic and a workaholic." Atwood said Black "was upset because about 10 days ago Joleen walked out and took the baby. She moved back with her mother. She wanted to live in a better place."

Atwood said when he left the station at 6 p.m. Monday, Black told him, "I think things are going to work out. Joleen's coming by with the baby and we're looking at a house in Harrandale."

State police said Beaty, who had the baby with her, picked up Black at the service station at 7:30 p.m. They drove away, returned and sat in the station parking lot, then left again and returned at midnight, when Black went into the garage and apparently got the 9 mm. Smith & Wesson automatic pistol from his toolbox.

Atwood, who identified the bodies, said Black and Pease were "good friends. I think when Chuck snapped, he didn't realize who it was, he just started firing" at Pease.

Atwood said Black told him "he didn't know how much he loved Joleen until she left.

"I knew he was having trouble because after she left, a tuneup that should have taken him an hour took two or three. But I had no idea he would kill himself."