People found guilty over a deadly rail accident in eastern India will be "punished stringently", the country's Prime Minister Narendra Modi has said.
At least 288 people were killed and more than 800 injured in Friday's incident in Odisha state, involving two passenger trains and a goods train.
Modi has visited the scene, labelling the incident a "painful" one.
He also met victims of the disaster in hospital, and vowed that his government would leave "no stone unturned for the treatment of those injured".
It is still not clear what caused the multi-train collision in Balasore district, which has been described as India's worst rail accident this century.
A full investigation has been launched, but a preliminary report indicates that the accident was the result of signal failure, said KS Anand, chief public relations officer of the South Eastern Railway.
Some 2,000 passengers are thought to have been on board the two passenger trains involved.
Officials say several carriages from the Coromandel Express, travelling between Kolkata (formerly Calcutta) and Chennai (formerly Madras), derailed at about 19:00 (13:30 GMT) after hitting a stationary goods train. It remains unclear how the Express ended up on the same track as the goods train.
Several of the Coromandel Express's coaches then ended up on the opposite track. Another train travelling in the opposite direction - the Howrah Superfast Express travelling from Yesvantpur to Howrah - collided with derailed carriages.