Fall River, Massachusetts - A nighttime fire at a nursing home has left nine people dead in the northeastern state of Massachusetts, local authorities said Monday.

The fire that broke out Sunday at an assisted living facility in the city of Fall River was "an unspeakable tragedy," Fall River Fire Chief Jeffrey Bacon told reporters.

"Nine people lost their lives in this building last night," Bacon said. "My thoughts and prayers are with the victims."

One person remains in critical condition, over 30 were taken to area hospitals, and at least a dozen were saved in a rescue requiring ladders, Bacon added.

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Five firefighters who were injured in the blaze have already been released from the hospital.

Firefighters who responded to the call shortly before 10 pm local time saw heavy smoke and flames at the front of the building with occupants trapped inside, the fire department said.

The origin and cause of the fire are being investigated.

According to The New York Post, Edward Kelly, President of the International Association of Fire Fighters, directly blamed Fall River's Mayor Paul Coogan for fire department budget cuts that may have contributed to the nursing home deaths.

The incident was "not only a tragedy, but a travesty," Kelly said in a press conference on Monday.

"Fall River Fire Department runs with 10 fire companies. Only two of them are staffed at national standards with four firefighters on those companies. The other eight fire companies only have three firefighters on them," he continued, adding that eight more firefighters would have been on the scene if staffing had been at the nationally recommended levels.

"Lives would have been saved if the Fall River Fire Department was adequately staffed," he insisted.