Safety violations including use of an open-flame torch near a leaky methane seal sparked a deadly underground explosion at an eastern Kentucky mine in May, authorities said Friday.

The protective seal was "poorly constructed" and failed to meet federal guidelines, according to a report from the state Office of Mine Safety and Licensing.

Five miners died in the May 20 explosion at the Kentucky Darby No. 1 Mine, a blast so powerful that it ruptured oil cans and broke mirrors on vehicles parked outside.

The torch ignited the leaking methane as two of the victims were repairing metal straps that intersected the top of the seal and were used as underground roof supports, the report said.

"In this case, what was done was clearly against regulations," said Susan Bush, commissioner of the state Department for Natural Resources.

The report said the two — mine foreman Amon Brock and maintenance worker Jimmy Lee — also shouldn't have been allowed to use a torch at that site because ventilation current passed through the area on its way to the surface.

Officials released the report to the public Friday, a day after giving it to the families.

Tony Oppegard, an attorney representing four of the victims' families, said the miners' widows still had unanswered questions about who ordered Brock and Lee to repair the straps.

"It didn't bring any peace at all. I think it was very difficult for all of them," Oppegard said Friday. "There was anger and sadness."

According to witness testimony, Brock had said they had to make repairs to the area before a federal inspector from the U.S. Mine Safety and Health Administration returned to the site two days later.

MSHA, which is conducting its own investigation into the blast, declined to let state investigators interview the inspector.

A lawyer for Ralph Napier, an owner of mine operator Kentucky Darby LLC, called the state's report incomplete.

"We disagree with many aspects of the report. But I don't want to get into specifics right now," attorney Kent Hendrickson said. "There's a more complete MSHA federal report to follow."

The federal report is expected by March, MSHA spokesman Dirk Fillpot said.