Chennai is confronting its worst crisis after overnight rain that has left most of the city flooded and people wading in almost waist deep water.
All flights have been suspended for the day and many trains have been cancelled.
10 latest developments
As lakes and reservoirs overflow, water level is rising alarmingly in some parts of the city. A major highway is flooded and no traffic is moving. The river Adyar is seen in images flooded almost to the edge of the bridge, which has now been shut down.
All flights have been suspended at the Chennai airport, where around 4000 people are stranded. The runway is flooded. At least 19 trains have been cancelled. The Army, the Navy, the Air Force and the National Disaster Response Force are out in Chennai to rescue people from their flooded homes.
"We have never seen so much rain and destruction in Chennai," said Union Minister of State for Home, Kiren Rijiju. Residents were seen climbing out of their homes or being pulled out to safety in the low-lying parts of Chennai where water is almost neck-deep. SOS messages on social media have led to rescues from buses, cars and rooftops.
Schools have been forced to close and exams have been postponed at least for this week. University exams have also been postponed. In many parts of Chennai, residents have opened their doors to strangers, offering food, shelter and even mobile recharges.
Malls, cinema theatres and offices opened their doors to stranded people. Prime Minister Narendra Modi spoke to Tamil Nadu Chief Minister J Jayalalithaa last evening and assured all help from the Centre.
"Spoke to Jayalalithaaji on the flood situation in parts of Tamil Nadu. Assured all possible support & cooperation in this unfortunate hour," PM Modi tweeted. Power supply in the city is very erratic.
People are stuck in many areas without food or water. Some residents formed convoys to help them. Chennai faces more rain in the next four days, said the Met office. It is the worst rain in Tamil Nadu in nearly 100 years.
The Chennai Corporation has announced Emergency Contact Numbers for all the regional zones in the city. People can contact the following numbers in case of any emergency due to the floods.