A Swiss Alpine guide and his Belgian companion fell about 500 meters to their death Friday while attempting to climb Mont Blanc, the highest mountain in the Alps, reported Italian police. The two men were working on a southerly attempt of the 4,810-metre tall mountain when they fell in the early morning, about 400 metres short of their goal. The cause of the accident is unknown. There were reports that, due to melting, that the snow on the mountain was particularly slippery Friday. Authorities also said a rockfall was a possible reason for the fall.