They buried 15-year-old Sean Smith yesterday. His grandmother shrieked his name so loudly it seemed to hang hauntingly in the sun-dappled church as teen-age boys and girls sobbed softly, their heads bowed, tears streaming down their faces.

"We have to do something to stop the killings and the madness. Our babies are dying," said Douglas Carter, assistant principal of Hamilton Junior High School, where Smith attended school.

"I want to talk to the young children," said Elder Lon Hamilton of Greater Pentecostal Church, addressing the friends of the teen-age youth, who was killed in an argument blamed on a stolen ski jacket. "When you understand you are your brother's keeper, you will stop killing your brother over anything. Don't let Sean's death be in vain.

"Let his life be a legacy!" Hamilton intoned, organ music punctuating his words. "The things he didn't have a chance to do, you do in his memory! He didn't get a chance to graduate; you graduate for him! He didn't get a degree; you get a BS for Sean! He didn't get a chance to write a book, but you go on and write a book. You be your brother's keeper!"

Smith lay at the altar in a blue casket, his Athlete's Foot employe identification card, which he had worn proudly, pinned to his gray suit, a floral arrangement with the Adidas logo at his head.

Hours later, a man suspected in Smith's slaying surrendered to D.C. police, according to a police spokesman. Tommie James Musgrove, 23, was charged last night with first-degree murder, police said. Musgrove lives at 1345 I St. NE, a block away from Sean Smith's home.

The funeral at New Southern Rock Baptist Church in Petworth drew nearly 200 people, including Smith's peers, some sitting between parents who whispered comfort, coworkers from the Athlete's Foot at Hechinger Mall and friends from the nearby Greater Pentecostal Church, which relatives and members said Smith joined when he was 12.

Smith's two brothers and his cousins, most youths with thin traces of mustaches, sat just feet away from the casket, their chins tucked in their collars. His closest friends, young men dressed in their best suits, bent to hug the neck of his sobbing grandmother, who sat with a nurse in a front pew and occasionally, overcome with grief, hollered, "Sean!"

Smith was shot to death on Dec. 28 in an argument that ended after he tried to question some youths, whom he had argued with earlier, about a jacket. Someone stole the coat while Smith was fighting one of the youths during the earlier argument. He was proud that he had bought the $99.95 red ski jacket with money he earned at the sporting goods store, where he was a sales clerk. He desperately wanted his jacket back.

His death was the latest in a series of homicides in which six youths have been killed in five months. The slayings, often by other youths, have sparked new concern about youths and guns, and the escalation of drug trafficking in the District, which police blame for the proliferation of guns.

Allen Mario Thompson, 18, Smith's cousin, also was shot in the incident last week. He remains in stable condition at D.C. General Hospital. The two were shot by a man with a handgun who approached them as they argued with a group of youths near their house at 1231 I St. NE.

Hamilton warned the youths that "fast money" usually means "fast death," and his admonishments against drugs brought applause and chants of "amen."

Carter, who said he spoke to Smith about his future just days before the youth's death, said later, "He had hoped to go to college. He was an average student and a very, very friendly kid. He wanted to work to do some things to help his grandmother. He was a very family-oriented child. He would do just about anything for his grandmother."

Rosa Brantley, Smith's grandmother, reared the youth, his two brothers and seven cousins with the help of daughter Stephanie Brantley. Rosa Brantley's husband died in 1971.

The family was reluctant to discuss all of the details about why the 10 boys lived with their grandmother. Stephanie Brantley said, "The court awarded the children to their grandmother when both of my sisters {Sean's mother and the mother of his seven cousins} were unable to care for them."

The first set of boys came to live with Rosa Brantley 12 years ago and the rest of them came shortly afterward. "We could not let the city or the federal government care for these boys," said their aunt. "We are family and we were determined to stay family."

Their grandmother stayed home with the boys while their aunt, now 27, worked to help support them. While she was in ninth grade, Stephanie Brantley went to Howard University through a special D.C. public schools program to study computers. After high school, she attended Prince George's Community College, with one goal in mind: To work to keep the boys together.

"I had my dreams of marriage and children, but I was willing to give that up because I felt you can't walk away from your family," she said, without bitterness in her voice.

"There were some Sundays when chicken would be frying in two pans, the washer and dryer would be going, and the boys would be ironing," Brantley said. "We always had two ironing boards up and two irons being used. They couldn't do chores after 10 a.m. on Sundays because that day was for resting."

The neat row house where the family has lived for 10 years is filled with books, games and trophies. Smith received two basketball trophies that sat on the fireplace mantle of the living room.

"We went fishing. My mother and I would fill our cars with boys and go to Salisbury, Maryland, to fish," said Brantley, who is manager of the production control department at Computer Data Systems in Rockville. "Sean loved to fish. My mother used a cane pole and the boys all had spin rods. I have even taken them hunting. I'd take them to the movies so they wouldn't ask to go to the go-gos. I would buy logs for the fireplace so they could sit in the living room and enjoy themselves."

Brantley said only one of the 10 youths has been in trouble with the police. An older cousin of Smith is in Lorton Reformatory on drug charges.

"We taught them to help each other and to help themselves," Brantley said. "Sean was the kind of boy who since he was 8 or 9 was always working. Once I went looking for him and found him in a store helping a man put prices on cans. It was like he was born knowing what to do.

"We tried to teach them right. Then you hear your kid is fighting and you run out and get him. At least, that's what's supposed to happen. You don't expect anybody to shoot him."