Three men whose hash oil manufacturing operation is alleged to have caused the fiery explosion that decimated the Hampton Greens apartment complex in Bellevue last year have been charged by the U.S. Attorney’s Office in conjunction with three other similar cases around the Puget Sound.

Part of “Operation Shattered,” U.S. Attorney Jenny Durkan announced the seven federal criminal charges filed this morning over four recent cases of hash oil explosions during a news conference in Seattle on Tuesday, saying her office and law enforcement will continue to fight the growing threat of illegal operations across the state.

“What the demand is creating is a public hazard,” Durkan said of consumer trends toward marijuana-infused products. “We will fight that public hazard.”

Residents at the Hampton Greens apartments awoke early Nov. 5 to the sound of an explosion that shook the complex and nearby businesses and residences, causing a fire that ripped through the KK building at 4505 148th Ave. N.E. A Bellevue Police investigative report states David R. Schultz, 32, Daniel J. Strycharske, 28, and Jesse D. Kaplan, 31, were residing in the apartment where the explosion occurred, caused by the ignition of butane gas inside that was part of a hash oil manufacturing operation.

Seven people were hospitalized that day, including former Bellevue Mayor Nan Campbell, who later died from injuries she suffered while fleeing the ensuing fire.

Schultz, Strycharske and Kaplan were charged Tuesday with endangering human life while manufacturing controlled substances maintaining a drug involved premises and manufacturing hash oil and marijuana. Durkan said neither state nor federal law allows the making of hash oil.

“If you’re doing it, you should stop,” she said, adding communities should be watchful of suspicious activities in their neighborhoods. “We see that it is a threat to those communities.”

Two people were also charged for an explosion and fire in Puyallup on May 20, and two others were charged with explosions and fires in Kirkland and Seattle that occurred in January. The news conference followed several morning arrests, where Durkan said some facing charges were found back at work making hash oil.

Campbell, 87, told responders at the Bellevue fire she tripped and fell while escaping the blaze, hurting her hip; a Kirkland firefighter noted burn marks on her robe. She died in the hospital on Nov. 19, 2013. The medical examiner’s office determined the cause of death was aspiration pneumonia and urinary tract infection due to prolonged hospitalization and immobility due to pelvic fracture with hematoma. She was elected Bellevue’s first female mayor in 1988 after serving two terms on the City Council. The explosion and subsequent fire caused $1.5 million in damage and the loss of $500,000 in belongings.

The Bellevue Police had forwarded its investigation to the King County Prosecutor’s Office in April, requesting attorneys consider filing second-degree manslaughter charges against Schultz, who was staying with Kaplan and Strycharske, and allegedly more involved in the hash oil manufacturing operation. Durkan said the U.S. Attorney’s Office could not find cause to charge the men with Campbell’s death, but there is no doubt her death would have been avoided had the hash oil operation not been started.

Schultz is alleged to have denied using the butane method of making hash oil, preferring isopropyl alcohol instead. Eight exploded cans of butane were recorded by investigators being found in the parking lot and shrubs around the apartment. Strycharske allegedly admitted to investigators that Schultz was “shooting” butane, using tubes and glass found inside their apartment, and that it could take up to five cans to do the job. Undamaged butane cans were also found, according to police and fire reports.

Bellevue Police reports also state an officer responded to the apartment complex Schultz was allegedly using to produce hash oil on Oct. 17, 2013 — three weeks before the explosion. A construction worker reported speaking to a man he witnessed assembling parts for what he said was a device for making hash oil for his dispensary. Documents state the officer went to the apartment and cautioned the occupants that making hash oil would be a violation of the lease, which was reportedly only held by one of the men there.

With medical marijuana and now recreational marijuana legalization in Washington, Durkan said law enforcement is facing “difficult terrain,” trying to better understand what is and isn’t allowed and how to respond to marijuana-related activities. She added there have been nine recent hash oil explosions reported in California, Colorado and Washington.

“I think the state is embarking on something that has never been done before,” she said of these law enforcement challenges.