TUXTLA GUTIERREZ, Mexico (CNN) -- Floodwaters in southern Mexico have killed dozens of people, and many more remained missing Wednesday night as rescue workers tried to reach some areas that were largely inaccessible.

Hardest hit was the state of Chiapas, where more than 28 people have drowned or died in mudslides in the past six days. At least 25,000 people in more than 50 towns and villages were driven from their homes, Gov. Roberto Albores Guillen said.

In the Pacific Coast state of Sinaloa, workers frantically tried to cut new escape routes for water that was threatening to overflow dams.

"We are very afraid that the death toll will increase. People are dying, because their houses suddenly were swept up," said Gilberto de los Santos, mayor of the coastal town of Pijijiapan, where 18 people reportedly died.

An exact death toll was impossible to determine, because many of the affected villages were in remote areas. But in addition to the 18 reported dead in Pijijiapan and 28 victims in Chiapas, at least seven deaths in other parts of the country were being blamed on flooding. More than 50 people were missing in Chiapas alone.

Southern Mexico was being battered by rains from Tropical Storm Javier, located in the Pacific, southwest of Baja California, and another tropical depression in the Gulf of Mexico. Areas caught between the two storms were receiving heavy rainfall.

Tapachula, a city near the Guatemalan border, received 18 inches of rain over the past three days

In Huixtla, a town near Tapachula, some residents huddled in their homes, ignoring calls by police to evacuate even as the swollen Huixtla River tore away and swallowed huge pieces of riverbank and the brick walls of homes.

Officials in Mexico City set up help lines and called for donations to aid those made homeless, many of them impoverished Indians.

President Ernesto Zedillo ordered 1,100 troops and two large jets carrying doctors, medical equipment and specialized personnel to go to Chiapas. Although rescue officials were able to reach parts of the disaster zone Wednesday, many other areas remained inaccessible.

Rising waters washed away many roads and bridges. Rain was falling so hard at Tapachula Wednesday that helicopters and airplanes could not fly, hindering the relief effort.

Reuters contributed to this report.