An escape of methane gas Monday at a coal mine in the northern Spanish region of Leon left six people dead, emergency services officials told Efe.

Four other people were taken to a hospital in Leon city after the 2:00 p.m. incident at the Pozo Emilio del Valle well.

Authorities are relatively confident that no other workers remain inside the mine, the sources said.

Local and national police, paramedics and a medevac helicopter were dispatched to the mine after the leak. Dozens of relatives and friends of the miners gathered at the gates of Pozo Emilio del Valle to await news. EFE