A home explosion Tuesday night in Tewksbury that sent three people to the hospital was caused by a drug cooking process that uses butane gas, according to the fire department.
Tewksbury Fire Chief Michael Hazel said Wednesday morning that the cause of the explosion and subsequent two-alarm fire was a marijuana THC extraction process that involves butane gas.
"The buildup of butane vapors within the apartment came in contact with an ignition source, and an explosion ensued," Hazel said in a statement. "The process was being performed on and around an electric stove within the apartment."
Multiple full and empty butane cylinders were found at the scene.
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"This was a very dangerous situation for the residents and the firefighters," Hazel said.
The explosion at an Astle Street home was reported about 9:15 p.m. When fire crews arrived there were flames coming from the home, and the rear windows had been blown out.
Two men and a woman were able to escape the home, but were seriously injured. They were flown by a medical helicopter to Boston hospitals.
Six people, including the three victims, were displaced because of the fire.
Authorities are investigating the incident.
Follow Michael Naughton on Twitter @metrobosmike.