ANNAPOLIS, DEC. 1 -- Two former standout athletes at the Naval Academy, football quarterback Alton Grizzard and distance runner Kerryn O'Neill, were shot to death this morning at the U.S. Naval Amphibious Base in Coronado, Calif., reportedly by O'Neill's former fiance. The gunman then shot himself to death, authorities said.

According to a Naval Academy spokesman, the killings took place at 1:45 a.m. PST in O'Neill's room in the bachelor officers' quarters, which house men and women. The base, across the harbor from San Diego, is headquarters for the Naval Special Warfare Command, which includes SEAL commando teams.

Coronado Police Lt. Bill Abel told the Associated Press there were no signs of a struggle and that all three died of head wounds. Abel said investigators believed Ensign George P. Smith had an argument with O'Neill Tuesday night. The San Diego Union-Tribune quoted Ensign David Lillefloren, a friend of Grizzard's, as saying that Smith was upset O'Neill had broken off her engagement to him.

Grizzard was in O'Neill's room after the quarrel, when Smith knocked on the door. Grizzard opened the door and was shot, Abel said.

Grizzard "was just a very close friend that she had associated herself with," Abel said.

The Naval Criminal Investigative Service was on the scene, as were homicide detectives from the Coronado Police Department.

Grizzard and O'Neill died inside a sixth-floor, one-room flat. Smith died as he was being taken to a hospital in an ambulance.

Residents of the barracks reported being awakened by the sound of six or seven shots, Abel said.

"There were three shots, then the sound of a woman screaming hysterically, followed by three or four more shots," Abel said. "Then it was over."

Two weapons were found in the flat, including a 9mm handgun that had been fired at least six times, officials said. Another gun was found in a jacket in the room and had not been fired.

Grizzard, 24, a lieutenant junior grade from Virginia Beach and a SEAL member, was Navy's quarterback from 1987 to 1990. He was the school's all-time total offense leader with 5,566 yards rushing and passing and became the fourth player in Navy history to rush for 2,000 yards in a career. In his senior year, Grizzard set a record by passing for 12 touchdowns; his total passing yardage for the season was 1,438 yards.

O'Neill, an ensign from Kingston, Pa., graduated with distinction in May with 12 varsity letters -- four for cross-country running, four for indoor track and field and four for outdoor track. She held academy records for the indoor and outdoor 5,000 meters and for the cross-crountry course and was the institution's woman athlete of the year for 1993.

Jason Van Matre, a member of the current Navy team, lived on the same dormitory floor as O'Neill last year. "She was just a great track star," he recalled. "And I never saw her in a bad mood."

Smith, 24, from Huntington Beach, Calif., was trained to work aboard nuclear-powered submarines and was assigned to Submarine Squadron Three. He also was a 1992 graduate of the Naval Academy, the Associated Press reported.

Football coach George Chaump, who arrived at Navy in Grizzard's final season, said he received the news about 10:30 this morning.

"I had to take a break from my meetings," Chaump said. "I walked around in a daze all day. It's hard to believe it happened. It's so bizarre....

"It's hard to believe he's gone. I visualize him popping back, his ol' cheerful self. Everybody loved him. He's the kind of player a coach gets the privilege of getting every several years.

"He exemplified everything great you looked for in a player. He's probably the toughest guy I ever coached. ... He had no fear and more mental toughness than anyone should ever have."

Chaump informed the team, which is preparing for Saturday's game against traditional rival Army in East Rutherford, N.J., during a meeting shortly before practice. Grizzard graduated in 1990 and was a teammate of this year's seniors.

Shortly before the announcement, the team had watched highlights of the 1989 Army-Navy game in which Grizzard led the Midshipmen to a last-minute triumph. In that game, Grizzard completed eight of 16 passes for 162 yards and rushed for 60 yards on 21 carries.

"It was a shock to most of us," said senior defensive tackle Ty Renick. "When someone dies like that, you don't really know how to react."

"My heart just dropped," said senior running back Van Matre. Added senior linebacker Javier Zuluaga, a member of the defensive scout team during Grizzard's senior year: "Crazy. How can three lives that young. ... How can it happen?"

Zuluaga and Van Matre, Navy's cocaptains, said the team is attempting to order stickers labeled "GRIZ" for the players to wear on the backs of their helmets for the Army game. Grizzard was Navy's co-captain in 1990.

"Obviously, we will be thinking about him a lot," Van Matre said. "He never gave up. He gave everything he had. He was a warrior out there. He was a player everyone out there tried to emulate."

Grizzard had returned on at least two occasions to speak with the team before games. One of those times was before last season's Tulane game, which Navy entered 0-7 but won 20-17.

He also visited before this season's Bowling Green game, another Navy victory.

After that Sept. 25 game, "I happened to turn around. He was on the sideline," said Chaump of the last time he saw Grizzard. "It was a good win for us. He had tears streaming down his face."

Jack Lengyel, the Naval Academy's athletic director, said Grizzard and O'Neill "exemplified all outstanding traits you would want an exemplary Midshipman to be."