A three-alarm fire broke out at a $13 million home in Brookline the day after Christmas and caused part of the roof of the 96-year-old mansion to collapse.

The blaze began around 10:40 a.m. at 90 Sargent Road on Dec. 26, according to a report from the Brookline Fire Department.

The home is valued at about $13 million, was built in 1928 and is about 13,000 square feet in size, according to the town assessor's office records.

Heavy smoke was coming from the attic of the L-shaped, three-story house when first responders arrived and a second alarm was struck, the fire department said.

All five people who were inside the home at the time were evacuated without injury.

Firefighters initially began to battle the flames inside the home, but they were forced to evacuate as conditions worsened. They continued to fight the fire from outside, according to the department.

A portion of the home's roof collapsed around 11 a.m. and caused the department to strike a third alarm for more resources, the department said.

The fire was finally extinguished after more than two hours of effort from the Brookline, Boston, Cambridge and Newton fire departments. No injuries were reported at the scene.

While the cause of the fire is still under investigation, it is not believed to be suspicious at this time, the Brookline Fire Department said.