A massive rescue operation is under way to reach stranded people in the flood-hit southern Indian city of Chennai (Madras).
More than 2,000 people have been rescued by the army, while the navy has decided to deploy a warship carrying divers, boats and relief material.
The city's airport will remain closed until Sunday and train services are suspended.
A depression in the Bay of Bengal has triggered rains in coastal areas.
Last month, non-stop rain for nearly a week brought the city to a standstill.
Three days of fresh rains have again led to massive flooding, inundating homes, hospitals, roads, railway tracks and the city's airport.
Schools, colleges and factories are shut, exams postponed and power supply suspended in most parts of the city.
Authorities said all flights to and from Chennai have been cancelled as the city's international airport will remain shut until Sunday.
A naval air base at Arakkonam, 70km (43 miles) from Chennai, will now be used as an alternative airport for relief operations.
"The biggest challenge is to find a way to clear the inundated airport and main roads," Anurag Gupta of the National Disaster Management Authority told the Reuters news agency.
The federal weather office has predicted three more days of torrential rains in Tamil Nadu, the southern state of nearly 70 million people.
"There will be no respite," weather official Laxman Singh Rathore told reporters.