What I always tell my residents to do: First, if you feel comfortable, ask them to keep the noise down, be polite (you never know who's packing these days).

Second: If they don't stop and you have a night manager, call. They get paid to manage the noise, emergency calls, lockouts, etc. at NIGHT!!! Do not hesitate to call for them to control the situation. If they feel as though it's so out of control or if they get more than one call on the problem, then they will call the police.