Several people were killed after a large fire broke out at an assisted living facility in the city of Fall River, Mass., on Sunday night, the authorities said.

The Fall River Fire Department responded to reports of a fire at Gabriel House, an assisted living facility, at about 9:50 p.m. Eastern time, said Jake Wark, a public information officer at the Massachusetts Department of Fire Services.

Firefighters encountered thick smoke and flames as they began trying to rescue residents who were stuck inside, Mr. Wark said. About 50 firefighters fought the five-alarm blaze, he added.

Multiple residents were pronounced dead at the scene, and many more were hospitalized, Mr. Wark said, calling the fire a “devastating tragedy.” Officials did not immediately release the number of victims.

Gabriel House opened in 1999 and has 100 units, according to records from the state of Massachusetts. About 70 residents had been living in the facility before the fire, and all of them were displaced, Mr. Wark said. He added that the cause of the fire was under investigation.

Fall River, a city of about 94,000 people, is near the border with Rhode Island.

This is a developing story.