Thousands of people were plucked from rooftops in southern Mexico on Sunday as water receded after flooding that left 800,000 homeless in Tabasco state, authorities said.

The army evacuated 5,000 people in a four-hour operation with 14 helicopters, police official Daniel Montiel said, as more food and bottled water was trucked in to crammed shelters that were struggling to provide enough meals and dry beds.

Army officials estimated another 80,000 people were still trapped in flooded homes, local media reported. Aerial images showed the area resembling a huge lake with just the tops of roofs poking through.

More than 30,000 people have been evacuated by the army and navy teams in helicopters or boats, civil protection officials said, despite problems with fog and rain and with flood victims trying to grab onto hovering helicopters.

Only one death has been reported in Tabasco, although in the poor southern state of Chiapas, local government officials reported four deaths on Sunday after rain-swollen rivers burst their banks, damaging thousands of homes and 16 bridges.

Tabasco Gov. Andres Granier said flood levels that had reached 19 feet at their peak were dropping on Sunday, despite drizzling rain. On Friday, people and livestock swam through streets neck-high in murky brown water.

Thousands of Tabascans fled by bus on Friday and Saturday to the neighboring states of Veracruz and Campeche, and tempers frayed among those left as people hunted for relatives and fought over dwindling food and drinking water supplies.

A supermarket in the state capital Villahermosa was looted and stores ran out of stocks, although water supplies were being restored and army helicopters dropped food packages into homes.

The floods, some of the worst the low-lying region has seen in 50 years, were triggered when heavy rain this week caused the Grijalva River to swell and burst through sandbags in the city.