A mine technician said Thursday he had no training when he helped build a wall to seal poisonous gas in an abandoned shaft at a southeastern Kentucky mine three months before five workers were killed in an explosion.

Unlike conventional seals made of concrete, the walls built at the Kentucky Darby Mine No. 1 were made with lightweight fiberglass blocks, and are a major part of the investigation into the May 20 blast.

Officials have said the explosion was fueled by methane gas and that the blocks did not withstand the blast.

Technician Tony Bledsoe, who was one of 26 Kentucky Darby LLC employees subpoenaed by state and federal officials for closed-door interviews this week, said he had worried about the unconventional seals.

"We weren't told how to build them," he said. "Our boss, he didn't stick around when we were building them."

He added that investigators at the hearing asked whether he and two other workers dug out a 4-inch slot into the coal wall and the ground to set the blocks into. He said he told them the workers had not.

Bledsoe also recalled that many of the blocks were broken when they were delivered. "The thing about mines — you use what they give you," Bledsoe said after meeting with investigators.

Another miner, Kevin Dixon, said he helped build two of the three seals destroyed in the blast. He said he and the other workers on the second shift learned how to construct the seals as they worked alongside their superintendent, Amon "Cotton" Brock, one of the men killed.

"If you're in the coal mine for 10 years, common sense tells you how to build them," said Dixon, who has worked in coals mines for a decade.

He said Darby was the first mine where he used the fiberglass blocks to seal a section of an underground mine that had been stripped of coal.

The U.S. Mine Safety and Health Administration has issued a moratorium on the unconventional seals in all mines.

The federal agency on Thursday also ordered that three eastern Kentucky mines be evacuated after a seal breach was discovered in one of the mines. No one was hurt. The breach was found at the Consol of Kentucky Inc.'s Jones Fork E-3 Mine in Knott County, MSHA said in a statement. Two adjacent mines — Ember Contracting's No. 10 mine and Abundance Coal Inc.'s No. 1 mine — were evacuated as a precaution.

"As announced last week, we are requiring that alternative seals be evaluated and corrective steps be taken wherever a hazard exists," David G. Dye, MSHA's acting administrator, said in the statement.

Family members of miners killed in last month's blast protested the meetings — which began Wednesday and were to continue through Friday — after state officials rejected a request to allow representatives of the miners' families to attend the interviews and ask the witnesses questions.

On Thursday, an attorney for the families demanded an apology from Gov. Ernie Fletcher and other state officials in a letter criticizing the "disrespectful and insensitive treatment of the widows and families."

U.S. Reps. George Miller of California and Ben Chandler of Kentucky, both Democrats, also issued a statement Thursday saying Fletcher should give family attorneys access to the interviews. They called for legislation setting uniform rules for all mining investigations.

Calls to Fletcher's staff seeking comment on the issue Thursday were not immediately returned. The Republican governor was out of the state on vacation.

The Darby mine has been closed since the explosion. Preliminary reports showed that three miners died from carbon monoxide poisoning, while the other two were killed by the heat and explosion.

Tony Payne was supposed to work at the mine the night the five workers were killed but had taken the shift off. The blast occurred just minutes after he normally would have started his job.

"It's hard to explain," Payne said as tried to describe how he felt about dodging the explosion. "I guess they'd be digging me out too."

Payne wouldn't elaborate on what he was asked during the private interview, only saying "they always ask about safety." The mine maintenance worker said he would continue to mine, but not at Darby, where the memories of his lost friends are too painful.