Tewksbury Fire Chief Michael Hazel said on Wednesday morning that a marijuana THC extraction process taking place inside an Astle Street home was the cause of the explosion that injured three people and destroyed the house.



Hazel said in a statement that the extraction process used butane gas, which led to a dangerous combination inside the home.



"The buildup of butane vapors within the apartment came in contact with an ignition source and an explosion ensued," said Hazel. "The process was being performed on and around an electric stove within the apartment."



Hazel said the incident remains under investigation, but added there were a number of full and empty butane cylinders found at the scene of the explosion.



Tewksbury Police Chief Timothy Sheehan was not immediately available when this story was published to comment on if any charges could result in the incident.



The house exploded at about 9:15 p.m. on Tuesday night, blowing out the windows, causing fire to spread to the attic, and requiring three Tewksbury residents who did not live at the home to be transported by helicopter to Boston hospitals.



"This was a very dangerous situation for the residents and the firefighters," said Hazel.



Check back with Tewksbury Patch for more on this story as it becomes available.