The experts had blunt and practical advice for school security personnel and other public officials from across Maryland and the District. First, they said, call a gang a gang -- not, as some educators have, a "criminally oriented youth group." Second, don't belabor distinctions between youths who are verifiable gangsters and those who aspire to become one.

"Wannabes are gonnabes," said Prince George's County police Sgt. George Norris. "A lot of the people that want to be a gang member are more dangerous than the actual gang members."

Although gangs are hardly new to the streets and schools of the Washington area, knife attacks this month in Montgomery and Prince George's counties have many educators wondering how to ward off gang violence when schools reopen in coming days.

Yesterday, police experts urged them to hunt for evidence that street gangs have penetrated schools and face the challenge squarely when it arises.

"It is critical that you have facts, and act on facts, and know what the facts are," Prince George's Police Chief Melvin C. High told a regional gathering of hundreds of education and security personnel at a Greenbelt high school.

"Anything we can do to help get the word out about gangs and the gang problem, we will," said Norris, a leader of a regional gang task force.

The conference's bracing message -- that gangs pose a threat in Washington area schools as much as they do elsewhere -- came with pledges from law enforcement and other public officials to redouble efforts to keep campuses safe.

A burst of gang-related stabbings Aug. 5 in Montgomery at a summer school campus and a shopping plaza -- and other crimes in the Prince George's immigrant community of Langley Park that may or may not have been tied to gangs -- have spotlighted school security. Classes in Prince George's resume Monday, with other area school systems following soon after.

"This is a regional problem," Prince George's County State's Attorney Glenn F. Ivey (D) told the audience. He touted a new Maryland law meant to give officials greater power to stop, or at least limit, gang recruiting in schools. "Start talking about how to implement it," Ivey said. "It could be a useful tool." He gave out his direct office telephone number and urged school officials to call him as soon as problems emerge.

Others offering help were U.S. Rep. Albert R. Wynn (D-Md.), aides to other members of Congress and an official from the U.S. Justice Department.

There was an air of worry yesterday among those gathered at Eleanor Roosevelt High School.

"It's scary," said Myra Martin, a school system worker based in College Park. "I'm very concerned about school starting because of the recent events in the area. I wonder if there are things brewing."

Frank Friedland, a Baltimore County school security officer, said evidence of rising gang activity there was sprayed all over school walls. "We're seeing graffiti in the back of the schools," Friedland said. "It's increased quite a bit in the past two years. It's a growing problem, without a doubt."

Experts said signs of emerging trouble could be found in such graffiti, or in the doodles of a notebook, or in subtle variations of colors, numbers or initials found on student caps and sports jerseys.

Graffiti tags from one gang, when slashed by a rival, can indicate an imminent turf battle, said Norris and Prince George's police Cpl. Michael S. Rudinski, who patrols Northwestern High School.

In student notebooks, they said, scribblings or illustrations often reveal gang affiliations. And synchronized wardrobes can publicly identify gang members or associates. The experts displayed jerseys, bandannas, baseball caps and other paraphernalia confiscated from gang members. There were, for instance, jerseys with the number 13, signifying the gang Mara Salvatrucha, or MS-13.

Rudinski used a visual projector to show security measures taken at the school on Adelphi Road. He said truants and gang members or associates frequently seek to converge on the campus in the afternoon when students are dismissed -- a time of heightened security alert.

He also advised educators to learn the language of gangs -- including hand signals and graffiti memos in bathrooms -- to pick up intelligence that may help avert violence. For instance, Rudinski said he asks students "who they roll with" or "who they beef with" to demonstrate his gang-lingo fluency.

The experts also said custodians can be valuable tipsters because they are more likely to have the trust of gang-associated students than a vice principal, teacher or security officer. They suggested giving custodians digital cameras to gather information.

One audience member lauded the conference for addressing the gang problem head-on. "It's here. It's real. We've got to do something about it," said Robert Foster, a Prince George's school investigator.

At the conference, Prince George's County State's Attorney Glenn F. Ivey urged school officials to call him as soon as problems emerge.