At least 324 people have been killed in flooding in the southern Indian state of Kerala, the regional chief minister says.
Rescuers are battling torrential rains to save residents, with more than 200,000 people left homeless in camps.
The state government said many of those who died were crushed under debris caused by landslides.
With more rains predicted and a red alert in place, the main airport has been shut until 26 August.
Hundreds of troops have been deployed to rescue those caught up in the flooding.
Helicopters have been airlifting people marooned by the flooding to safety, with photographs and footage emerging from the area showing elderly people and children being rescued.
More than 300 boats are also involved in rescue attempts, AFP news agency reports.
The government has urged people not to ignore evacuation orders, and is distributing food to tens of thousands who have fled to higher ground.
Chief Minister Pinarayi Vijayan has described the flooding as the worst the state has seen in 100 years.
"We're witnessing something that has never happened before in the history of Kerala," he told reporters.
"Almost all dams are now opened. Most of our water treatment plants are submerged. Motors are damaged."
He added that the failure of the state government of neighbouring Tamil Nadu to release water from a dam had made the situation worse.
Kerala has 41 rivers flowing into the Arabian Sea, and 80 of its dams are now said to be open.
Mr Vijayan said more than 223,000 people were now living in the more than 1,500 emergency relief camps set up in the area.
Parts of Kerala's commercial capital, Kochi, are underwater, snaring up roads and leaving railways across the state impassable.
Its airport is a hub for domestic and overseas tourists, so its closure is likely to cause major disruption.
Some local plantations are reported to have been inundated by water, endangering the local rubber, tea, coffee and spice industries.
Schools in all 14 districts of Kerala have been closed and some districts have banned tourists citing safety concerns.
The Indian home ministry says more than 930 people have now died across India since the country's monsoon season began in June.
Anil Vasudevan, the head of the Kerala health disaster response wing, has said they are prepared to help victims and are setting arrangements in place to deal with the potential risks of water-borne diseases when the flooding recedes.