MOUNT VERNON, Wash. -- Police say an attempt to extract hash oil from a marijuana plant caused an apartment explosion in Mount Vernon Thursday that blew the windows out at an apartment and sent at least three people to the hospital.
It happened around 11:45 p.m. at the Ridgewood Apartments in the 400 block of Stanford Drive.
Mount Vernon police say officers arrived to find flames coming from one of the units. The impact of the blast sent glass several feet into the parking lot and walls were forced off their studs.
Lt. Chris Cammock says the injured people drove themselves to Skagit Valley Hospital. Cammock believes a fourth person also checked themselves in later with injuries. None of the injures appear to be life-threatening.
The Washington State Patrol bomb squad investigated to make sure there were no other explosives.
The complex was evacuated for two hours to determine which units were safe to return to. Five units remained closed for the investigation.
Police say the process of extracting oil from marijuana involves mixing parts of the plant with butane gas. It appears a two-liter pop bottle was being filled with butane when Thursday s explosion happened.
The method of using butane to extract hash oil from marijuana is so popular and dangerous that the Federal Emergency Management Agency (FEMA) issued an unexpected alert to emergency responders across the country.
Followers of this method squirt butane from canisters into tubes containing marijuana. The butane forces the oil out of the marijuana, which they collect and process into hash oil. Hash oil is a very concentrated form of marijuana that produces powerful effects from just a small amount. It produces very little smell and is easy to carry around.
Fire officials say the problem is when the process is carried out indoors. The excess butane, they say, is heavier than air and builds up on the floor until it reaches a ignition source. Explosions capable of blowing out windows and walls can result.