After working more than 25 years in Pennsylvania's coal mines, Dale Reightler was anxious to open his own auto repair shop and build that race car he and his friends had always talked about.

"And now, this," said Charles Kimmel, Reightler's lifelong friend and brother-in-law. "Now, we might just build a race car and let his two boys run it. In memory of him."

Reightler was killed Monday in an explosion half a mile underground in an R&D Coal Co. anthracite mine in a remote, mountainous region of Tremont Township, about 80 miles northwest of Philadelphia.

Five other miners escaped, authorities said.

It appeared the blast occurred when miners detonated explosives, said Dirk Fillpot, spokesman for the federal Mine Safety and Health Administration. The miners had checked for methane gas before the morning detonation, but did not detect any, he said.

The accident knocked out the mine's ventilation system, making it too dangerous for investigators to go down into the shaft. Officials hoped to restore the ventilation system by Tuesday so they could get a firsthand look at the damage.

The five miners who escaped, including the foreman, were being interviewed, said Mark Carmon, a spokesman for the Department of Environmental Protection. He did not have any information about what they told investigators.

A June inspection turned up no safety violations, while an August inspection found brush surrounding an exhaust fan that was cleared while the inspector was on site, according to the DEP.

Less than two years ago, four workers at the same mine were injured by flying debris and coal from an explosion caused by a pipe with a faulty gauge, according to state officials. R&D was allowed to reopen after installing safety equipment following the accident.

Eastern Pennsylvania has the nation's only deposits of anthracite, a type of hard, relatively clean-burning coal that once heated millions of homes but now represents a sliver of the U.S. coal industry.

The anthracite mines that still exist are typically very small operations employing only a handful of miners.

Federal and state regulators ordered the mine closed until the investigation is complete.

Reightler, who had worked in the mines since high school, leaves behind a wife and four children.

There have been 41 other deaths in U.S. coal-mine accidents this year, according to the Mine Safety and Health Administration. The deadliest was in January, when 12 were killed at the Sago mine in West Virginia.