A 20-year-old man found fatally shot Tuesday on a playing field at a Northwest Washington high school was slain after a confrontation with members of a Latino street gang, police and city officials said yesterday.

Willian Pineda Lazo suffered multiple gunshot wounds in the 2:30 p.m. attack near a track surrounding the football field of Roosevelt High School. A 16-year-old male from Maryland also was shot but survived, police said. Neither victim was attending the school, but a family member said that Lazo once was enrolled there.

D.C. police initially believed that the shooting stemmed from a fight at a school assembly, but sources said yesterday that that turned out not to be true. Instead, a police source said yesterday, Lazo and some companions were approached on or near the field by a group believed to be members of the Vatos Locos street gang.

Members of the Vatos Locos group asked Lazo's group if they were part of another gang that often gathered near the field, the police source said. Those in Lazo's group said they were not, but the shooting ensued anyway, the source said.

One arrest warrant, for a 20-year-old man, has been obtained for first-degree murder while armed, the police source said. Authorities hope to obtain warrants for three other suspects soon, according to the source.

Theodore Tuckson, acting director of security for D.C. public schools, said authorities reviewed footage from 28 security cameras inside and outside the school, but found nothing useful. Most of the school's 821 students were at an assembly in the auditorium when the gunfire began.

D.C. Council member Adrian M. Fenty (D-Ward 4) said Lazo's death could mark the fourth time that a Latino male was killed in gang-related violence this year in the ward. Last year, he said, there were no such incidents.

"My community is scared, I'll be quite frank, about the increase of gang activity," Fenty said, noting that Latino gangs are more common in Columbia Heights but were not previously seen as far north as the shooting site, near 13th and Upshur streets NW. "People are scared . . . because it's so new," he said.

Lazo, of the 4100 block of 14th Street NW, was a Salvadoran immigrant who followed his parents to the United States when he was 8, according to his cousin, Maria Flores Pineda. Pineda said Lazo had dropped out of Roosevelt.