LEXINGTON ? A Lexington home exploded in a ball of fire Wednesday after an apparent natural gas leak, prompting the fire department to evacuate 1,500 homes in the area.

The house, located at 3 Hancock Ave., is owned by Dr. Elliot Thrasher, a surgeon at Massachusetts General Hospital, and his wife Antra Thrasher.

Antra Thrasher and her son escaped the blast with minor injuries, said Fire Chief William Middlemiss, adding that they were ?fortunate to get out.?

?The son, from our understanding, was working inside the house. He heard something pop. He went downstairs. He smelled the odor of gas. As he exited the building, the building exploded,? Middlemiss said.

The mother was reportedly outside raking at the time of the explosion. They were both treated at Massachusetts General Hospital.

Firefighters from Lexington, Waltham, Bedford, Belmont, Burlington and Hanscom Air Force Base battled the roaring blaze for about two hours. The two-story house was burned to the ground.

Middlemiss said crews from gas company KeySpan Energy were working to shut off the natural gas in the area. He said the system ?overpressurized? at some point Wednesday morning and that ?overpressurization led to the explosion.?

A shelter was set up by the Red Cross at a local high school for the evacuated residents.