NEW YORK, NY November 11, 2009 —Members of the NYPD were at a school in Harlem last night to address what they see as an ongoing problem - the growth and increased sophistication of gangs. WNYC's Arun Venugopal was there.

REPORTER: The Gang Intel event, as it was called, was a sort of primer on the dozens of small gangs operating in Harlem and beyond, with names like the Cash Money Brothers or Goons on Deck. Some are limited to specific housing developments, while others comprise only girls, or even Muslim youth.

A police expert says some gangs are buying special backpacks for their guns, with secret compartments that even officers can't detect. Herma Hall, the principal of Harlem's Wadleigh High School, says gangs are by no means an epidemic, and tend to be home grown, but that communities should recognize the signs before they become an entrenched problem.

According to the NYPD, crime in Northern Manhattan is down 14 present for the year. For WNYC, I'm Arun Venugopal.