MILTON, Mass. (AP) _ The slaying of a high school tennis star who police believe may have been killed because he informed on gang members has stunned this peaceful suburb.

The killing of Charles Hardison, 16, was only the second in 20 years in this affluent town just south of Boston's inner city, Milton police said.

''Charles had the personality that every man in the world would like to have,'' said Jim Smith, who coached Hardison in tennis for the past eight years. ''If you could bottle it, you could make a million dollars. He was destined to be a leader.''

Hardison's mother, Adlene, went to wake him Thursday morning but found his bed had not been slept in. She found him in the basement with four gunshot wounds, three to the head, police said. There was no sign of a struggle, robbry or forced entry, leading investigators to believe that Hardison knew his killer, police said.

Mrs. Hardison had arrived home the previous night and found her son's keys in the lock. Neighbors said he often forget to remove his keys from the lock. Mrs. Hardison apparently assumed he'd gone to sleep.

Students at Milton High School, where Hardison was the top-ranked tennis player, said the shooting may have been connected to an incident last year in which members of a Boston gang crashed a party given by a friend of Hardison's. The party later turned violent.

Hardison, reportedly angered because one of his friends was injured, cooperated with police, pointing out the home of the girlfriend of one alleged gang member, some students said.

A Milton police officer said Friday that the department was investigating the possibility of a gang link in the killing. Boston Police Deputy Superintendent William Celester, who runs the police station in the gang- plagued Roxbury section, said Milton police had contacted detectives there about the killing.

School officials said Hardison was not involved in gangs or drugs and had never been a discipline problem.

Student anger over Hardison's death spilled over into an assembly Thursday, a school official said.

At the assembly, one student denied that her boyfriend, reportedly a gang member, had killed Hardison, said Vice Principal Paul Dorsey.

''(Other students) walked out as the girl was speaking,'' he said. ''My interpretation might have been that they didn't believe her.''

Eva Price, a neighbor of the Hardisons who had known Charles since he was 5, said the youth recently had helped a neighbor clean up his yard.

''I looked out my window Sunday morning and said 'I don't believe it.' He was helping him rake his leaves,'' she said pointing to an adjacent lawn. ''He was working harder than the guy's son.''

Price said the killing raised concerns for the safety of her own three teen-agers, even on a street where birdcalls are louder than passing cars.

''Everybody wants to know what triggered this,'' she said. ''I won't let my kids stay alone here, not until police tell me what happened. It does worry us.''

Price also said she disagreed with neighbors who declined to talk to reporters. ''He's a wonderful kid. He died a violent death and it should be known that he was into (good) things,'' she said.

School officials said Hardison, who was black, helped found the high school's Students of African Descent. He was also the top-ranked tennis player in the Bay State League, school officials said.

''He was truly an outstanding tennis player,'' Dorsey said.

Smith said Hardison played outstanding tennis while on a club-sponsored trip to the Soviet Union last August. Hardison won all five of his matches, leading the team to a 32-22 win over the Soviet teams.