Discuss as:

Major fire chokes Boston's Back Bay; hotel evacuated as smoke spreads

Boston Fire Department

Flames burst through a garage housing a 115,000-volt transformer in Boston's Back Bay.

Updated at 9:08 p.m. ET: A 390-room hotel was evacuated, major streets were closed and residents were urged to seal their windows Tuesday night as crews battled a four-alarm transformer fire in downtown Boston.

Boston Medical Center said "several patients" were treated for smoke inhalation, WBZ-TV reported.

The fire erupted about 6:30 p.m. ET in a garage in Back Bay, a neighborhood known for its meticulously preserved 19th-century brownstone homes and other architectural landmarks, including the Boston Public Library, NBC station WHDH reported.

The garage is just around the corner from the Back Bay Hilton, which was evacuated as thick black smoke poured from the 115,000-volt transformer. Transit stations and major roads, including Boylston Street and Massachusetts Avenue, were closed.

Officials, after earlier warning people to stay away from the smoky fire, said the transformer that was ablaze was cooled with non-toxic mineral oil.

“While not toxic, it is never good to inhale any kind of smoke,” the department tweeted.


Several city blocks were without power after the fire department ordered electricity shut off to the area so the fire could be confronted.

Smoke from the blaze dissipated mid-evening, the fire department reported about 9 p.m.

Electric utility officials said they would work on restoring power to 20,000 customers once they had a clear assessment of damage in the burned substation. The fire caused a problem at a second substation, officials said.

More content from msnbc.com and NBC News

US News on msnbc.com on Twitter and Facebook