The explosions -- which happened in Bellevue, Kirkland, Seattle and Puyallup -- injured a number of bystanders and caused thousands of dollars in damage.
Hash oil is typically made by packing the castoff leaves and stems of pot plants into a pipe and pouring highly flammable butane through it. The concoction is heated to make the potent oil for far cheaper than it can be purchased in stores.
Without proper ventilation, butane fumes can linger. All it takes is a spark of static electricity to ignite a room.
Three people were charged Tuesday in connection with a Bellevue explosion and fire on November 5, 2013.
Former Bellevue Mayor Nan Campbell was hospitalized for a broken pelvis she suffered trying to escape the flames. She later died following complications after her hospitalization, according to prosecutors.
Two other apartment residents suffered shattered bones as they had to jump from their upper level apartments.
David Richard Schultz, 32, Daniel James Strycharske, 28, and Jesse D. Kaplan, 31, were all charged with endangering human life while manufacturing controlled substances, maintaining premises and manufacturing hash oil and marijuana, according to U.S. Attorney Jenny A. Durkan
"Everyone of these home based systems is a violation of federal law and state law. If you're doing it, you should stop," Durkan said.
Seth Cleek, 31, and Kevin Weeks, 24, were also charged in connection with a hash oil explosion in Puyallup and May 20. Prosecutors say the duo makes and sells marijuana edible products, and the explosion put a number of people in danger, including a 14-month old child.
Robby Wayne Meiser, 46, and Hugh Rodney Harris, 65, were charged in connection with explosions in Kirkland and the Mount Baker neighborhood of Seattle.
"These deadly explosions are reckless and preventable acts," DEA Special Agent in Charge Matthew G. Barnes said in a Tuesday news release. "As marijuana cultivation activities increase, explosions will continue. DEA will stand by our law enforcement partners in stemming this dangerous threat."
Endangering Human Life While Manufacturing Controlled Substances is punishable by up to ten years in prison and three years of supervised release; Maintaining a Drug Involved Premises is punishable by up to 20 years in prison and three years of supervised release and Manufacturing Hash Oil and Marijuana is punishable by up to five years in prison and three years of supervised release.