The sun finally broke through rain clouds in southern Mexico on Friday, giving relief teams the first chance in days to fly to flooded villages, where they discovered dozens more dead.

The death toll in Chiapas state rose to more than 100 Friday. Twenty thousand people had been forced from their homes, and nearly 500,000 were cut off by washed-out roads and downed bridges, Interior Secretary Francisco Labastida said in Mexico City."A situation this serious, this severe has not occurred in Chiapas in almost 50 years," said Labastida, who is in charge of domestic security. At least 50 Chiapas communities had no means of communication.

Eight days of rain - from storms in the Pacific and the Gulf of Mexico - provoked flooding believed to be the region's worst in at least half a century. Others called it Mexico's worst disaster since a 1985 earthquake killed thousands in the capital.

More than a dozen people were reported dead in the states of Nayarit, Jalisco, Sinaloa, Guanajuato and Oaxaca.

With Chiapas' road system broken by surging rivers and mudslides, the government sent aid into Guatemala to be carried back north by truck.

The Tapachula airport bustled with activity. Crews unloaded boxes of aid from a half-dozen military cargo planes. A dozen helicopters stood ready to ferry the supplies to affected regions.