NEW YORK (CBSNewYork) — Last weekend’s blood bath at two separate house parties in Brooklyn has the NYPD cracking down.

Police Commissioner Ray Kelly said that apartments are unable to handle large parties and widespread advertisements for the gatherings created the potential for “overcrowding issues.”

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“Obviously you’re going to be concerned about that,” Kelly said.

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Kelly said precinct commanders were keeping a closer watch on social networking chatter on Facebook and Twitter. He blamed the websites for allowing guest lists to grow, leading to unintended consequences.

“Every weekend we pay close attention to parties all over the city,” Kelly said. “It’s sort of a growing phenomenon and something we pay a lot of attention to.”

The police commissioner also said that the ads often make statements like “no I.D. needed.”

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Kelly said that authorities check out many of the venues ahead of time, but admitted some of them slip through the cracks.