WASHINGTON (AP) — A congressional committee on Friday subpoenaed two of the owners of Utah's Crandall Canyon Mine, where six miners died in a roof collapse last August.

The subpoenas order Robert E. Murray, CEO of the Ohio-based Murray Energy Corp., and P. Bruce Hill, president of UtahAmerican Energy, to give depositions on March 18-19 or on another mutually agreed upon date.

Lawmakers have been investigating what happened at Crandall Canyon last Aug. 6, when six miners were trapped 1,800 feet below the surface of the canyon. It was never learned if the miners survived the initial cave-in, and their bodies have yet to be recovered. Three others were killed as rescuers tried to tunnel toward the trapped miners.

"Our goal in speaking with Mr. Murray and Mr. Hill is the same as our goal in this investigation — to learn what went wrong at the Crandall Canyon Mine so that we can apply lessons learned from this tragedy to ensure that nothing like it happens again," said Rep. George Miller, D-Calif., and chairman of the House Education and Labor Committee.

Murray Energy issued a statement saying it is cooperating with Miller's committee and others investigating the tragedy.