The 2-alarm fire broke out just after midnight on the unit block of Brookline Drive.
Crews arrived to heavy fire throughout the house. Neighbors reported seeing fire blowing out from the corner of the house.
A father, 65, mother, 58 and their two daughters, ages 24 and 25 managed to get out of the house before it collapsed.
They say they heard an explosion in the basement.
It took firefighters about an hour to get the blaze under control.
Investigators believe a gas line ruptured, causing an explosion and the massive fire.