SPENCER, Mass. (AP) _ A priest on Friday told teen-agers attending the funeral of a classmate who shot himself that they should not dwell on their mistakes.

''Sometimes you fumble,'' said the Rev. Richard Ritacco, who was holding a football as he spoke at the service at St. Mary's Roman Catholic Church for Francis V. McNamara, 16, who played on the school football team.

''Sometimes you forward it to a touchdown. Sometimes you win. Sometimes you lose. But there is something more important than winning. It's how you play the game,'' Ritacco said.

McNamara, a junior at David Prouty High School, died Tuesday at Worcester City Hospital, a day after he shoot himself in the head with a .22-caliber rifle.

Two classmates, a girl, who slashed her wrists, and a boy, who drank iodine, also attempted suicide over the weekend, the police said. They said the incidents were unrelated.

Lifting the football, Ritacco said, ''This football has no meaning when it is created. It is nothing until it is inflated and begins to take shape and form and meaning. It has no purpose until someone puts it into his hand. Frank McNamara did that. He gave this ball purpose.''

He urged the boy's schoolmates, including six teammates serving as pallbearers, not to dwell on mistakes or fret about the future but to trust in God and be concerned with the present.

''If Frank were here standing before us, as I am sure God is letting him, I am certain he would say I am sorry,'' Ritacco said. ''I love you and do not forget me for I will not forget you.''

School officials, who have been available to speak with students about the suicide, said they feared for students' well-being during next week's school vacation in this town of 10,700.

''We're very much afraid of what might happen Friday afternoon when they no longer will have school faculty to talk to,'' school Superintendent Philip F. Devaux told about 200 parents Thursday night in the high school cafeteria.

The 750 students at the school will be allowed to congregate Tuesday through Friday in the gymnasium, where counselors and a policeman will be available to speak to them.