BOSTON (Reuters) - At least 17 people were injured as a nine-alarm blaze raged through a four-story building in the city's historic Back Bay neighborhood on Wednesday, drawing a large-scale emergency response, local officials said.

All residents of the apartment building escaped unharmed, said Boston Fire Department spokesman Steve MacDonald. He described the fire as a nine-alarm incident, the department's highest level of severity.

With more than 150 firefighters at the scene, it was not immediately known how many of the injured may have been civilians, he said.

"It's a very unstable condition right now," MacDonald told reporters earlier. With the winds, "it's hard fighting it from the outside."

Boston Emergency Medical Service said it had taken 17 people to area hospitals.

Of the injured firefighters brought to area hospitals, one was listed in serious condition, MacDonald said.

Firefighters were focused on keeping the blaze from spreading to neighboring buildings on a day the city was buffeted by high winds, MacDonald said.

Live television video showed an enormous plume of smoke rising from the building, and hovering over the city. State police said they closed a major roadway along the Charles River behind the burning building.

(Reporting by Scott Malone; Editing by Gunna Dickson)

Update: WBZ-TV reported that two firefighters were killed by the blaze. A report aired earlier in the day on Wednesday can be seen below.