Indian Prime Minister Narendra Modi promised that the government would "leave no stone unturned" in response to the Odisha train crash that killed nearly 300 people and injured more than a thousand others.
During a visit to the crash site at Balasore, around 220 kilometers (137 miles) southwest of Kolkata, Modi told local media that "stringent action" would be taken against anyone found to have caused Friday evening's disaster.
He said the incident would be probed "from every angle."
The crash, which involved two passenger trains and a freight train, was India's worst rail disaster in more than two decades.
What is the latest from the crash site?
As night fell in eastern India on Saturday, Odisha Chief Secretary Pradeep Jena told Asian News International (ANI) that the rescue operation was almost complete.
Emergency workers have spent more than 24 hours combing through the mangled wreckage for survivors and laid scores of bodies out under white sheets beside the tracks.
Jena said the rescue effort was slowed because two train carriages were pressed together by the impact of the accident.
He added that the death toll reached 288 and the major challenge was now to identify the bodies.
"Wherever the relatives are able to provide evidence, the bodies are handed over after autopsies. If not identified, maybe we have to go for a DNA test and other protocols," Jena said.
An official from the Balasore emergency control room said all the bodies and injured passengers have now been removed from the crash site.
Sudhanshu Sarangi, director general of Odisha Fire Services, said the death toll was expected to rise further, potentially approaching 380.
Local media reported that around 800 injured people remain in the hospital, while more than a hundred who sustained minor injuries were discharged.
About 200 of the most severely injured were transferred to specialty hospitals in other cities in Odisha, reports said.
Amitabh Sharma, a Railroad Ministry spokesperson, said authorities would now start removing the wreckage to repair the track and resume train services.
Ashwini Vaishnaw, India's railway minister, said a high-level probe was underway.
Prime Minister Modi flew to the crash site and spent half an hour examining the relief effort and talking to rescue officials.
He later visited a hospital where he walked around talking to doctors and the injured.
Saturday was declared a day of mourning in Odisha.
What caused the rail crash?
There are conflicting accounts about how the disaster unfolded.
The Press Trust of India (PTI) reported that the Howrah Superfast Express train running north from India's tech hub Bengaluru to Kolkata derailed first, falling onto the adjacent southbound track. Minutes later, the Coromandel Express heading from Kolkata to Chennai smashed into the wreckage.
Some of its coaches also collided with a goods train parked alongside, PTI added.
A preliminary report indicates that the crash was the result of signal failure, K. S. Anand, chief public relations officer of the South Eastern Railway, said, giving a slightly different order of events.
"The Coromandel Express was supposed to travel on the main line, but a signal was given for the loop line instead, and the train rammed into a goods train already parked over there. Its coaches then fell onto the tracks on either side, also derailing the Howrah Superfast Express," Anand said.
Chaotic scenes erupted after the derailment as rescuers and local residents climbed atop the wrecked trains to break open doors and windows using cutting torches.
Rescue teams, helped by the army and military helicopters, raced throughout the night to free the hundreds of people trapped in the rail cars under the twisted metal and broken glass.
India struggles to rebuild colonial-era railway
The accident happened as the government seeks to modernize the rail network, much of which was built during British colonial rule.
Despite government efforts to improve safety and upgrade the railway infrastructure, several hundred accidents occur every year.
The worst was in Bihar in 1981 when a train derailed while crossing a bridge and plunged into the river below, killing between 800 and 1,000 people.
Friday's crash ranks as the country's third-worst, and the deadliest since 1995, when two express trains collided in Firozabad, near Agra, killing more than 300 people.
Most train accidents are blamed on human error or outdated signaling equipment.
According to operator Indian Railways, more than 20 million people ride trains across India every day, traveling on 126,000 kilometers (78,000 miles) of track.