At least 38 people are now known to have been killed by a series of bomb explosions in the city of Ahmedabad, in the western Indian state of Gujarat, police have said.
Officials say there were 17 blasts within an hour, targeting residential areas, public transport, market places, and hospitals where the injured were being treated.
It is thought the explosions were caused by crudely-made devices hidden in boxes and on bicycles.
TV footage showed the side of a bus damaged by a bomb, with its windows shattered and roof blown off.
Many of the victims were hit by flying ball-bearings and other shrapnel packed into the bombs.
Local media reports say a little-known Islamist group called the Indian Mujahideen has claimed responsibility.
A BBC correspondent in Ahmedabad says many people are not leaving their houses because of fear of further attacks.