SAN DIEGO (AP) _ A fired worker fatally shot a company labor representative and critically wounded his former supervisor after turning up at an aircraft plant for a grievance hearing, police said.

Robert Earl Mack, who worked at the General Dynamics plant for 25 years, surrendered after holding police at bay Friday for about 20 minutes. He was booked on murder and assault charges.

Mack, who was fired Jan. 15 for poor attendance, made it past company security checks with a concealed .38-caliber revolver and shot the two in a courtyard as other employees looked on, said homicide Lt. John Welter.

''I don't think he shot at random,'' he said.

Mack had gone to the employment office for a routine grievance hearing about his firing, said George Roos, vice president of human resources. The meeting involved company representatives and the International Association of Machinists, Welter said.

After shooting Michael Konz, who later died, and wounding James English, Mack walked into a Convair Division office with two workers inside and held police at bay, Welter said. Police persuaded him to surrender.

Workers said the mood has been tense at the plant since the company announced in May it would lay off thousands of workers because of defense cutbacks.

Mack assembled Advanced Cruise Missiles in the Convair Division, which was hit by layoffs late last year and faces more layoffs by March. Mack wasn't among workers laid off, Welter said.

''It was sort of expected .... that someone was going to go off,'' said employee Saad Binno. ''A lot of people there that's the only job they've ever held.''

Konz, 25, was a labor representative in the human resources department and English was Mack's former supervisor, Roos said.

English, 52, was in critical condition at the University of California, San Diego Medical Center, nursing supervisor Jane Swett said.

Plant worker Maria Alvarado said she was about to leave for the day when someone shouted, ''Get back 3/8 Somebody has a gun, and he's shooting 3/8''

Workers took cover wherever they could, she said.

''Fear was in everybody's face,'' she said. ''You didn't know who was going to get hit.''