2 dead, another injured after being trapped in house fire in Upper Dublin Township, Pa.

UPPER DUBLIN TWP., Pennsylvania (WPVI) -- A husband and wife have died and their adult son is in the hospital after a fire in Montgomery County's Upper Dublin Township early Thursday morning.

The couple has been identified as 74-year-old Stephen Wood Sr. and 70-year-old Deborah Wood.

Crews were called to the 900 block of Bellaire Avenue in Upper Dublin Township just after 4 a.m.

Action News has been told that when the fire broke out, their 35-year-old son, Stephen Wood Jr., was able to escape and run to a neighbor's house. However, his two parents, who were inside at the time, became trapped.

When fire crews arrived, heavy fire was seen coming from the second floor of the single-family house.

The fire marshal says the couple, along with the family's dog, died inside the home.

"One was extricated from the first floor, but was a fatality at that time. The other one we could not find during the firefight, and through the investigation we were able to discover the body and turn that over to the coroner's office," said Upper Dublin Township Fire Marshal Timothy Schuck.

A neighbor told Action News off camera that the victims who died were wonderful people and beloved in their community.

Action News also learned Stephen Wood Sr. co-owned a bar in Philadelphia with his brother.

Stephen Wood Jr. is being treated in the burn unit at Temple University Hospital.

The fire marshal says they believe the fire started in the back of the home, in a sitting room, where Deborah Wood stayed because of a disability she had.

Officials said part of the second-floor bedroom collapsed during the fire and that the home is a total loss.

Crews spent hours on the scene Thursday morning working to dig through the debris. They say they are working to determine the cause of the fire, which remains under investigation at this point.