Emergency responders arrived at the scene of an explosion on Astle street in Tewksbury shortly after 9 p.m. Tuesday.
Investigators now believe drugs may be the cause of the explosion.
A preliminary fire investigation shows that there was a buildup of butane gas that ignited and exploded inside the home. It's believed that someone inside was using that butane gas to extract THC from marijuana.
Police have not confirmed if this is a criminal investigation.
Police said three people were injured and flown to Boston hospitals with burns, their conditions are not known.
“We had three victims, two males and a female airlifted from here to Boston hospitals. They had burns about their heads, hands, face area,” Tewksbury Police Chief Tim Sheehan said.
The blast was strong enough to blow the windows out from the historic home dating back to the 1800s.
Witnesses told police they saw two people running from the house before the explosion. Police have not confirmed that report.