WATERTOWN, MASS. (WHDH) - A three-alarm blaze ripped through an apartment complex in Watertown on Friday morning, causing part of the roof to collapse.

Video from SKY7 HD showed firefighters on ladder trucks working to extinguish the flames as they shot through the roof of the building on Robert ford Road. A large plume of smoke could be seen billowing into the sky.

Firefighters struggled to get the flames under control but the raging blaze has since been knocked down.

Crews from Boston, Waltham, Newton, and Cambridge helped Watertown firefighters battle the blaze.

Michelle Burns, who lives next to the public housing building, says she heard screams as the chaotic scene played out.

“I heard screaming, flew down my stairs, opened my backdoor and just saw three units engulfed,” Burns recalled. “I’ve never seen anything like this in my life.”

There were no reported injuries but one resident was hospitalized with an unrelated health issue, Watertown Deputy Fire Chief Thomas McManus said.

A dozen units were charred in the blaze and 31 people were displaced.

The cause of the fire remains under investigation.

This is a developing news story; stay with 7NEWS on-air and online for the latest details.

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