The youngsters at a community meeting in Southeast Washington were in unfamiliar territory. They had been invited to talk about crime prevention when, ordinarily, they’d be hanging out on the streets while others talked about them.

“I want to thank our young people for coming out,” said Dionne T. Reeder, who helped organize the meeting last week at the Anacostia Public Library. “We look forward to hearing what you have to say.”

But the youngsters never got the chance. Someone from a neighborhood gang known as Choppa City appeared outside a library window and began pointing them out as rivals from a group called the Lench Mob. Organizers halted the meeting and began scrambling to head off a melee.

As the drama unfolded, however, the youngsters would reveal more about themselves than they ever would if the meeting had gone on as planned.

The 10 of them had barely noticed the applause that followed Reeder’s compliment; most were seated in the back and looking down at their cellphones. The recognition that seemed to matter had come from the window.

A finger pointed through a pane of glass had revealed their true identity and thrown the room into a panic.

Asked why the two groups were feuding, one of the youngsters told me, “That neighborhood don’t like us.” To which another added, “Like we care.”

A recent spate of street fights in Anacostia, and two shootings in uptown Woodley Park, including one outside the National Zoo, had left residents shaken and in search of answers. Why are scores of youngsters having mega-melees in Southeast? Why do hundreds more go to the zoo just to fight each other, taunt the animals and intimidate the tourists, and even shoot into a crowd after being kicked out by zoo security?

“It hurts me to see 60, 70 youths in the middle of the street fighting,” said Reeder, who is program coordinator for the Far Southeast Family Strengthening Collaborative.

Assistant D.C. Police Chief Diane Groomes, who also attended the meeting, spoke of “hundreds and hundreds” of youngsters gathering in the streets.

Some get together because there is safety in numbers. Others seem to enjoy being a part of a group so big that it can’t be ignored.

“I’ve never seen such large groups of people,” she told me later. “Back in the day you had large numbers of people hanging out on a corner, but they tended to stay there. These kids move all over the place, and there are so many of them they can take over a street.”

The honk of motorists’ horns becomes music to their ears. “I see you,” it says.

Choppa City is a loosely knit group of unruly youths who live in Anacostia, while their counterparts in the Lench Mob reside in the Woodland Terrace housing complex about a mile away. The turf is divided by Good Hope Road SE, which intersects with Martin Luther King Jr. Avenue. The library where the meeting was held is on the Choppa City side of the street, at 1800 Good Hope Rd.

So is Anacostia High School, which draws students from both neighborhoods.

It is a ridiculous distinction, but one that organizers of the meeting regret not taking seriously enough.

“We shouldn’t have brought them down into another group’s territory,” said Dina Callahan, an outreach worker with the family collaborative who helps girls in both neighborhoods. “But we still need to hear from them. They need attention so badly but they are isolated, just stuck in a box, with no outlets, nothing to do.”

Since the start of the school year, D.C. police have responded to 86 incidents involving fights and threats of violence in the community, many of them involving the two gangs. The police have mediated 150 less serious disputes and made about 200 home visits to let parents know that their children were starting to hang with the wrong crowd.

Still, the problem is getting worse. The crowds are growing. Choppa City has even sprouted an offshoot of younger members who call themselves Cruddy Bang.

Organizers at the library meeting decided not to take any chances. The youths were escorted to a van and driven back to Woodland Terrace.

Robin Hoey, a D.C. police commander whose 7th District includes Lench Mob turf, watched as the youngsters left the meeting, their expressions a mix of pride and defiance. He’d seen the two groups go at it before and knew that some provocations weren’t intended to end in violence. For all anybody knew, one of the youngsters may have alerted Choppa City to their presence with a photograph posted online.

“The mind-set of some of these kids is amazing,” he said. “They know exactly what they are doing. They want attention and they are getting a kick out of this.”

For previous columns, go to washingtonpost.com/milloy.