More than 100 people have died in five days of heavy rains in the southern Indian states of Tamil Nadu and Karnataka, officials say.
Scenes of disruption in Tamil Nadu
More than 50,000 people have been evacuated from their homes in affected areas of Tamil Nadu.
Thousands of people have been displaced and air, rail and road services hit.
Weather officials have warned of more rains in Tamil Nadu because of a cyclone that is due to hit coastal areas of the state on Friday.
Many parts of Tamil Nadu are under water and reports say strong winds have uprooted trees and hit power and phone lines in some parts of the state capital Madras.
"We seem to be passing from one disaster to another since the tsunami," state relief commissioner R Santhanam told Reuters.
Schools and colleges in the two states have been closed and more than 250 government schools converted into temporary shelters.
Officials say 60 people have died in flood-affected areas of the state.
Heavy rains in the neighbouring state of Karnataka have led to the flooding of the Cauvery river which flows into Tamil Nadu.
Residents in the state capital, Bangalore - also India's technology hub - are also battling floods after three major lakes in the city breached their banks.
Schools in the city were closed and several apartment complexes flooded. Water entered some office-buildings, including one of the offices of India's third largest software exporter, Wipro.
Bangalore accounts for one-third of India's annual export revenue of $17.2bn in software and back-office outsourcing.
Officials say more than 40 people have been killed in the state.
The coastal states of Orissa and Andhra Pradesh have also sounded an alert.
"Heavy to very heavy rainfall accompanied by squally winds with speeds of 55-65 km (35-40 miles) per hour in north Tamil Nadu and south Andhra Pradesh are expected," says meteorologist SR Ramanan.