New Delhi - The southern Indian metropolis Chennai was crippled Wednesday by floods brought on by torrential rains that left thousands stranded in their homes and shut down the city's airport.
"The situation may worsen in the next 24 hours. Flights are grounded, trains are cancelled ... it is an unprecedented situation," federal Urban Development Minister Venkaiah Naidu said in parliament.
The Indian navy was carrying out rescue and relief operations along with the army, local government and disaster management personnel, Defence Minister Manohar Parikker said.
Television footage showed victims being helped to climb down from first floor windows onto makeshift rafts or swimming to rescue boats in low-lying areas, where the water in some places reached above 2.4m.
Roads looked more like rivers with only the tops of cars visible in some areas.
Chennai is the capital of Tamil Nadu, one of India's most industrialised states. It is an economic hub for the region, with a port and international airport and a population of about 4.6 million.
"Our first floor is mostly under water, there is no power and the mobile phone charge is running out," schoolteacher Sudha Ramesh told dpa.
"My father is 85 and a cardiac patient, we are waiting to be rescued for six hours now, please pray that it stops raining," she said from Chennai's Munambakkam neighbourhood, which has seen 294mm of rain since Tuesday.
All flights from Chennai airport, including connections to international destinations, were suspended until Thursday when the situation would be reviewed, an official at the airport control room said.
At least 700 people were stranded at the airport which handles around 350 flights a day, the NDTV news channel reported.
Schools and colleges were closed in the affected areas as were factories and offices after the rains, caused by a low-pressure system over the Bay of Bengal.
Twenty-three trains had been cancelled and eight diverted, railways information officer Anil Saxena said. The railways was trying to provide drinking water and food to passengers stranded on trains and at stations.
The Hindu newspaper, a Chennai icon, failed to print for apparently the first time in its 137-year history as workers could not reach the printing plant, NDTV reported.
The power supply had been cut off in some areas, including to hospitals, while in others residents have had no access to food or water, the broadcaster said.
Chennai citizens living in safer areas offered the shelter of their homes and to distribute food on Twitter where #ChennaiRains and #ChennaiFloods were trending through the day.
Fifteen teams of the National Disaster Relief Force were carrying out rescue operations in Chennai, the organisation's chief OP Singh said.
"The airport being closed is making things difficult," Singh said. Efforts were on to send more personnel and equipment through the nearest airport at the temple town of Tirupati.
The navy had already deployed several motorised boats and personnel, spokesperson Aloke Bhatnagar said. Helicopters and drones stationed on ships near the Chennai coast were on standby.
A naval warship with more personnel, medical supplies and other equipment would be arriving on Thursday from the port of Vishakhapattanam.
"The rainfall is likely to continue for another two days according to our data. The situation is not encouraging," LS Rathore, director general of the Indian Meteorological Department said in New Delhi.
Rathore said Chennai's airport was in a low-lying area so it would be difficult to resume flights till the rains stopped and the water was drained from the runways.
Chennai has high average rainfall in November but this year it has seen more than double of the seasonal average, Rathore said.
Another spate of heavy rain in mid-November also brought the city to a temporary standstill.