A remark about a girl appears to have triggered an argument between rival gangs that later escalated into violence at Springbrook High School last week, a senior law enforcement official said yesterday.

The two gangs -- identified by the law enforcement official as Mara Locos and Mara Salvatrucha, or MS-13 -- are usually eager for any pretext to clash, and the remark started an argument Friday between the gangs during the summer school session at the Colesville area school, the official said. The official spoke on condition of anonymity because the case remains open.

After school let out, the members of Mara Locos and MS-13 continued the argument, and a fight broke out near a parking lot, the official said. Two teenage boys were stabbed.

Four hours later, members of the two gangs met by chance three miles away at Westfield Shoppingtown Wheaton, and the MS-13 members, having heard about the earlier fight, attacked their rivals, the official said. That fight left four teenagers with knife wounds.

MS-13 members appeared to be the aggressors in both fights, police say. All six victims are expected to live.

Another suspect in the Springbrook stabbing was arrested yesterday, bringing to 12 the number of young men and teenagers charged in the two incidents. Wilber Garcia-Martinez, 19, of the 8200 block of 14th Avenue in Hyattsville has been charged with conspiracy.

Two defendants, Santos M. Garcia, 28, charged in the Springbrook attack, and Alexis Rodriquez-Marquez, 15, charged as an adult in the Wheaton incident, were ordered held without bond yesterday by Judge Thomas L. Craven.

Charging documents show that Garcia is a known member of MS-13, bearing a tattoo of "MS" on a hand and a large "MS 13" on his back. Prosecutor Jeffrey T. Wennar said members of MS-13 contacted Garcia to help with the stabbing at Springbrook.

According to the charging documents, a witness identified him from a photo array and told police that he saw Garcia advance aggressively toward victim David Gamero.

Garcia's attorney, Charles B. Lipscomb, said Garcia has held a steady job as a tree cutter for about six years and had disassociated himself from MS-13 for several years.

"Even if Mr. Garcia was involved, it was at a minimal level at best," Lipscomb said.

The day's violence has drawn renewed attention to the street gang problem in Montgomery County.

A 2004 report by a joint Montgomery-Prince George's county gang prevention task force estimated that Montgomery had 20 to 22 active gangs with 540 to 560 active members and associates.

Although gangs are present in all police districts in Montgomery, they are most heavily concentrated near Langley Park, Takoma Park, Wheaton, Rockville and Gaithersburg, the report said.

Patrick Word, a Gaithersburg police detective, said that assaults and robberies are the most common gang-related crimes targeting ordinary citizens. Beatings and murders usually occur among gang members, particularly in retaliation for a perceived insult, he said.

On June 26, a group of at least 10 MS-13 members stabbed and beat a man on a soccer field at Gaithersburg Middle School. The 30-year-old victim was not a gang member or an intended target, Word said, but he may have been with people whom the gang was seeking.

Word said the MS-13 members, who shouted their gang affiliation as they attacked, were looking for revenge on someone who showed signs of disrespect to them at a party.

No arrests have been made in the case because witnesses have been afraid to come forward, Word said.

"Everybody was there, but nobody saw anything," he said.

Staff writer Phuong Ly contributed to this report.