A high school senior set to graduate next week spotted a girl outside a convenience store in Prince George's County early yesterday and offered to buy her a Slurpee. That gesture of teenage amicability apparently cost the student his life.

According to Prince George's County police, the offer led to an attack in which Michael Antonio Bassett, 18, was beaten, kicked, knocked down and left on a road in Suitland where at least two cars struck him.

People who knew the Oxon Hill High School student said he was friendly and outgoing, perhaps a flirt, but not a troublemaker.

"It will be a sad graduation," said Gwendolyn Miller, a parent involved with his class. "Not a happy one."

Police gave this account: Bassett and two friends headed to the 7-Eleven at Silver Hill Road and Plaza Drive about 3:15 a.m.

As Bassett approached the store, he noticed a girl standing outside. He offered to buy her a Slurpee, and she accepted.

A man who was nearby overheard the conversation, got angry and shouted threats. Bassett apologized several times, and he and his friends tried to leave.

But the man, and as many as seven others who appeared to be in their teens or twenties, blocked their path and began punching Bassett and his friends.

The two friends, described as 17-year-olds, managed to escape. But Bassett was pursued for two blocks along Silver Hill Road.

At one point, several shots were fired at him. He was not hit by any of the shots, but his pursuers apparently caught up with him in the 5200 block of Silver Hill Road.

"They beat him and kicked him until he fell to the ground," a police spokeswoman said.

Bassett was left lying in the street. It was not clear whether he remained conscious.

At least two cars struck him, and when police arrived about 3:30 a.m., they found him dead.

The police investigation continued late yesterday, but no arrests were reported.

Bassett was "a good student . . . a very nice kid" who was outgoing and "got along with everybody," said Randy Ware, a teacher at Oxon Hill, who is a sponsor for the graduating class.

Jeanine Bassett, the slain student's mother, also called her son "a very outgoing person."

She said he worked as a lifeguard at an apartment complex, was talkative and could "make you laugh in a minute."

It was that gregariousness, she said, that probably prompted him to ask the girl if she wanted the Slurpee. "He was a flirt," she said.

She said that Bassett and his friends went out every Saturday night and that he was supposed to be home by 3 a.m. But she said she fell asleep and was awakened about 4 a.m. by a phone call from some of his friends.

A school system spokeswoman said grief counselors will be on hand when school resumes tomorrow.

Deborah A. Franklin, an assistant principal at Oxon Hill, called Bassett "a very lively young man with a beautiful smile.'' She said he had been an office assistant for her and had matured greatly in the past year.

"We're very devastated by Michael's death," Franklin said.

She added that she could "just imagine him trying to do something kind for the young lady," and then, in apologizing, trying to put into practice the peer mediation techniques taught at the school to defuse disputes.

"Maybe someone else had not quite matured enough to learn that," she said.