Laura E. Lee Cyrus R. Vance Jr.

Fighting crime — on the Internet or on the street — takes community cooperation, said Manhattan’s district attorney, Cyrus R. Vance Jr., who spoke to residents at the 9th Precinct Community Council meeting Tuesday night.

Addressing a crowd of about 40 people at the precinct stationhouse, Mr. Vance said individuals have to be diligent about protecting personal information from identity theft. “The Internet is the crime scene of the 21st century,” he said.

While cybercrime is a real threat, Mr. Vance said the 500 attorneys in his office are continuing to collaborate with the local precincts to combat the more traditional crime involving “guns, gangs and drugs.”

Deputy Inspector Kenneth Lehr, commanding officer for the precinct, emphasized the need for citizens to take preventative action against crime as the weather grows warmer.

He warned the audience of some of the daily hazards in the summer, like leaving a window open or not keeping a careful eye on personal items at sidewalk cafes. Residents should be on the lookout for any unknown individuals on fire escapes and alert officers to their presence, he said.

Several residents voiced concerns about criminal activity in the region, mostly focused on underage drinking and drunken activity in the early morning hours.

“Underage drinking is a tremendous problem for us,” Inspector Lehr said. When police tested local bars for serving minors, 64 percent passed, he said.

The Council does not meet in July or August.