A landmark building on the Lower East Side was evacuated Monday evening after firefighters responding to a smoke alarm noticed floors were shaking and beams were cracked inside, setting off concerns over possible instability, officials say.

Crews were called to The Angel Orensanz Center at 172 Norfolk St. at about 7:30 p.m. for a smoke alarm going off, according to FDNY Deputy Chief Jim Hodgens on the scene. Firefighters determined the alarm was set off by smoke from cooking.

While they were investigating, firefighters were notified that the floors above were shaking, Hodgens said. Firefighters discovered several beams were cracked, signaling a possibly unstable structure, and immediately began evacuating the building.

About 500 people had to leave the building.

The building is a former synagogue that was restored as an art gallery and performance space in the 1980s, according to the venue's website.

"It was a very fortunate situation that we were on the scene and a potential disaster was averted," Hodgens said.

The Department of Buildings said Tuesday that an inspection showed vertical cracks in floor joists on the first and second floors. The building is under a full vacate order until repairs can be made.