A probe of the worst coal mine cave-in accident in 21/2 years began Friday with a federal official saying that one survivor saw the accident coming but was too late to save the three miners who were killed.

"He tried to warn the others, but the fall came too quick," U.S. Mine Safety and Health Administration spokesman Joey Lucas said Thursday of Roger Wilder, 37, of Cubbage.Wilder, who was operating machinery with an overhead canopy and was not harmed in the accident Wednesday, saw the overhead dipping and tried to alert the others when the roof caved in.

Wilder was trapped for about 20 minutes until other miners cleared fallen rock and shored up the roof, Lucas said. The cave-in occurred as the men were removing coal about 2,400 feet into the mine.