The NYPD is concerned about tweets that warned that people would be killed at boxer Mike Tyson’s one-man show. One tweet referenced the shootings last month in Aurora, Colo., that left 12 dead in a movie theater.

NYPD spokesman Paul Browne said Tuesday that Twitter initially refused to disclose the source of the posts. He says the social media site has since turned over information in response to a subpoena, but he provided no further details.

A Twitter spokeswoman declined to comment.

Police recently beefed up security at the Long Acre Theater in midtown Manhattan as a precaution.