A piece of the facade at 15 E. 17th St. fell off the building and landed on the sidewalk below. View Full Caption Trevor Kapp//DNAinfo.com

UNION SQUARE — A landmarked building on East 17th Street is in the process of being vacated after a piece of its facade broke off and plummeted onto the sidewalk below on Monday evening, forcing tenants out of their homes without any idea of when they'll be allowed back in.

Pieces of decorative masonry fell from the top of the six-story building at 15 E. 17th St. roughly 6 p.m., city officials said. While no one was hurt, Laut Thai restaurant on the ground floor was forced to vacate along with the residents of the lofts above, according to a spokesman for the Department of Buildings and a chef at the restaurant.

The current masonry was deemed unsafe by DOB's forensic engineers on Monday. The residents will not be allowed back into the building until the issue is resolved, according to the spokesman.

"When I came out [last night], there were two or three pieces of concrete on the ground," said Mike Chim, the 59-year-old chef of the restaurant. "They were about 1-foot long. It's lucky there were no people there."

As of Tuesday afternoon, Laut was fully vacated, and the residents were in the process of leaving the building, a DOB spokesman said.

A scaffolding was installed over the sidewalk in front of the landmarked building by Tuesday morning and the sidewalk immediately outside of the building was closed off.

The DOB slapped the building's owners with an Environmental Control Board violation for failing to maintain the building's exterior, the DOB spokesman said.

The owner of the property as listed on the deed, Triad Capital LLC, did not immediately respond to requests for comment.

Chim arrived at the restaurant, which serves Thai and Malaysian cuisine and usually opens at 11 a.m., Tuesday morning in hopes of opening the restaurant, but was stopped by police who were standing outside, he said.

"If they say we can't open, I have to go home," Chim said.