A Shrewsbury property owner, a realty trust and an asphalt company have been sued for allegedly causing a dangerous explosion and fire in 2017 that released hazardous material and fumes during the demolition of a storage shed, and for failing to notify authorities or take necessary cleanup actions, Attorney General Maura Healey announced Thursday.

The complaint, filed in Suffolk Superior Court, alleges that the defendants – Edgar Muntz Jr.; 393 Oak Street Realty Trust, which Muntz owns and manages; and the Sutton-based contractor P&M Asphalt Services Inc. – illegally demolished a backyard shed at Muntz’s Shrewsbury property, even though the shed was filled with hundreds of containers of hazardous material, including dynamite, mercury, arsenic, chloroform and sodium cyanide. During the demolition, the shed burst into flames, releasing the hazardous material into the air and soil. The AG’s Office also alleges that the dangerous release of toxins caused workers and a neighborhood resident to develop respiratory problems.

“The careless and illegal actions of these defendants put the health of workers and nearby neighbors at serious risk – and left the state responsible for the cleanup,” Healey said in a statement. “We have filed this lawsuit to ensure that all necessary steps are taken to restore this property and keep the public safe.”

After a neighbor alerted authorities about the explosion, the Massachusetts Department of Environmental Protection, along with other state and local agencies, responded to the scene and took remedial action to secure the site and clean up the hazardous materials.

“MassDEP expended significant resources to contain and control a release of hazardous materials in a dense residential neighborhood due to the failure to properly remove hundreds of bottles and containers of chemicals and hazardous material before demolishing the backyard shed, putting neighbors and workers at risk to exposure,” MassDEP Commissioner Martin Suuberg said in a statement.

The AG’s Office claims that the defendants violated the Massachusetts Oil and Hazardous Material Release Prevention and Response Act and the Massachusetts Hazardous Waste Management Act by causing the release of hazardous material, failing to notify the MassDEP or any emergency response authority, and failing to take any actions to mitigate the release of hazardous material into the air.

Through this lawsuit, the AG’s Office said it is seeking “substantial” civil penalties, damages and an injunction requiring the defendants to comply with state law and to conduct further necessary cleanup actions at the property.