Boston firefighters knocked down a heavy fire in Dorchester Monday afternoon, as the rear porches of a multi-family home collapsed.

The Boston Fire Department responded to the heavy blaze in the rear of 37 Holiday St., before 4 p.m. on Labor Day.

The fire reportedly extended to the building next door and in the rear, and a fourth alarm was ordered for the heavy fire.

“The rear porches of 37 Holiday St. have collapsed, all companies are working,” Boston Fire tweeted.

After 4 p.m., the fire department reported that the heavy fire had been knocked down on all three of the buildings.