Firefighters battle Upper East Side blaze at building housing Serbian Mission to the United Nations

UPPER EAST SIDE, Manhattan — Firefighters battled flames at an Upper East Side building on Sunday night.

The blaze broke out at 854 5th Avenue, which houses the Serbian Mission to the United Nations.

The building has three floors. It is currently for sale.

Firefighters first got a call about the fire at 8:40 p.m., officials said. It quickly escalated to a 2-alarm blaze.

"Southbound 5th Avenue is CLOSED at East 68 Street due to @FDNY activity," police tweeted. "Please avoid the area & use alternate routes."