Rescuers in boats and helicopters worked early Friday to evacuate people stranded by a flood the president called "one of the worst natural disasters" to hit Mexico.
A week of heavy rains caused rivers to overflow, leaving 70 percent of the Gulf state of Tabasco underwater, and forcing thousands of people to cling to rooftops or flee to shelters. It is the worst flooding the state has seen in 50 years.
Nearly all services, including drinking water and public transportation, were shut down in the state capital, Villahermosa, 80 percent of which was underwater.
"The situation is extraordinarily grave: This is one of the worst natural disasters in the history of the country," President Felipe Calderon said in a televised address Thursday night.
The rain had stopped Thursday, but weather forecasters predicted more precipitation in the coming days. The flooding was not related to Tropical Storm Noel, which pounded the Caribbean.
The Grijalva River, one of two large waterways ringing Villahermosa, has risen 6.5 feet above its "critical" level and gushed into the city's center. Authorities said some of the rivers were continuing to rise.
Rescue workers in boats and helicopters plucked desperate residents from their rooftops and led thousands to shelters, but the task was proving to be more than they could handle.
Of the estimated 700,000 people whose homes were flooded, damaged or cut off, 300,000 still had not been rescued Thursday and potable water supplies were exhausted in Villahermosa, Tabasco Gov. Andres Granier said. Police, soldiers and military workers were still trying to reach them.
In Villahermosa, dozens of survivors anxious about relatives and friends crowded outside government offices seeking assistance. Others waded despondently through waist-deep water or wandered along highways leading out of the capital.
"We lost everything," said Manuel Gonzalez, whose house was swallowed by the floodwaters early Thursday. "I left without one peso in my pocket and I can't find my siblings."
The state of Chiapas, which borders Tabasco to the south, also reported serious flooding, with officials there estimating that more than 100,000 people had been affected.
Calderon asked Mexicans to contribute bottled water, canned goods, diapers and other vital supplies to donation centers around the country.
"Nobody can stand around with his arms crossed," Calderon said. "We can't and won't abandon our brothers and sisters in Tabasco."
