A Massachusetts man allegedly murdered his wife and three young children and then set his home on fire before killing himself, a district attorney said.

The bodies of Luke Karpinski, his wife, Justine Wilbur, their 7-year-old twins, Alex and Zoe, and 3-year-old son, Marek, were found in their home in Sheffield in western Massachusetts on March 13. The deaths were ruled a murder-suicide.

Luke Karpinski via Facebook

Berkshire County District Attorney Andrea Harrington said in a press release on Monday that investigators found "evidence of accelerant in different parts of the home," including two 20-pound propane tanks on an upper floor.

“This investigation is complex and ongoing, but we have uncovered overwhelming evidence suggesting that Luke Karpinski killed his wife and children prior to committing suicide,” Harrington said Monday.

Wilbur, 41, was found dead on the first floor of the house with a "traumatic injury," the district attorney said. Karpinski, also 41, and his children were found dead on an upper floor.

Authorities have not revealed the cause of deaths, and autopsy reports for the couple and their children were not available on Tuesday. The Berkshire Eagle reports that Wilbur and her children may have been stabbed to death. Harrington said in the press release that a gun was not found in the home.