The army, air force and navy launched massive rescue and relief operations, pressing helicopters, transport aircrafts and ships along the eastern coastline and in island territories to search for the dead and trapped.
This is the first time India has been hit by tsunamis, which are triggered by seismic disturbances -- coastal earthquakes, volcanic eruptions or undersea landslides -- that jolt the ocean floor. The result is a deep wave that stretches from the sea's surface to the floor and travels horizontally at speeds of up to 800 km/hr and rises between 50 and 100 ft.
People walk in a flooded street in Chennai.
Also read: Tsunamis kill more than 6,000 in Asia