A Twitter user who threatened to carry out a massacre like the one in Aurora, Colo., at a theater in Manhattan is being sought by the police.

The New York Police Department is planning to subpoena microblogging site Twitter for the user's identity, after the user threatened to "kill a lot of people" at the Longacre Theatre in Midtown.

The Twitter user, whose identity, age or gender are not yet known, claimed on the site to be creating a "hit list." Boxer Mike Tyson is also performing a one-man show at the venue.

NYPD Deputy Commissioner Paul Browne said the police's Intelligence Division learned of the threat late on Aug. 3. He said police used an "emergency system" provided by Twitter to request the user's identity but that did not work because the NYPD did not have a subpoena. 

"Twitter turned us down, so we dispatched police to cover the theater while we sought a subpoena to force Twitter to disclose the identity of the account holder," Browne said. "We take the threat seriously, especially in light of recent attacks in Wisconsin and Colorado."

The Manhattan district attorney's office reportedly also plans to subpoena Twitter for the information this week. The District Attorney's office declined to comment. 

Twelve people were murdered last month and scores of others injured when suspected gunman James Holmes walked into the Century 16 movie theater in Aurora and fired into the crowd of moviegoers watching "The Dark Knight Rises."

And white-power extremist Wade Michael Page killed six people and wounded four during a shooting at a Wisconsin Sikh temple on Sunday.

The NYPD has beefed up security at the theater.

Twitter spokeswoman Carolyn Penner said the company has no comment on this issue.

Twitter's site does spell out guidelines for law enforcement seeking information in the site's users.

According to those guidelines, user information held by Twitter is private, and, in order for the police to get its hands on it, a "subpoena, court order or other valid legal process to disclose information about our users" is required.

Many Twitter users have public profiles with information accessible to anyone, but apparently the author of the Manhattan threat did not.