Families of the victims of India’s deadliest train crash in decades filled a hospital in Bhubaneswar city on Monday to identify and collect bodies of relatives, as railway officials recommended the country’s premier criminal investigating agency to probe the crash that killed 275 people.

Distraught relatives of passengers killed in the crash Friday lined up outside the eastern city’s All India Institute of Medical Sciences. Meanwhile, survivors being treated in hospitals said they were still trying to make sense of the horrific disaster.

Outside the hospital, two large screens cycled through photos of the victims, their faces so bloodied and charred that they were hardly recognizable.

Each body had a number assigned to it, and relatives stood near the screen and watched as the photos changed, looking out for details like clothing for clues.

Many of them said they had spent days on desperate journeys from neighboring states, travelling in multiple trains, buses or rented cars to identify and claim bodies, a process that stretched into a third day due to the gruesome nature of the injuries.

So far only 45 bodies have been identified, and 33 have been handed over to relatives, said Mayur Sooryavanshi, an administrator who was overseeing the identification process at the hospital in the capital of Odisha state, about 200 kilometers (125 miles) south of the site of the train crash in Balasore.

Upendra Ram began searching for his son, Retul Ram, Sunday, after traveling some 850 kilometers (520 miles) from neighboring Bihar state. The day-long journey in a rented car, which cost him 35,000 rupees ($423), was exhausting for Ram, who said Retul, 17, had been on his way to Chennai to find work.

After spending hours looking at photographs of the dead, Ram identified his son around noon Monday.

“I just want to take the dead body and go back home. He was a very good son,” said Ram, adding that Retul had dropped out of school and wanted to earn money for the family.

“My wife and daughter can’t stop crying at home. They are asking me to bring the body back quickly," he said, wiping tears from his eyes with a red scarf he had tied around his head.

Friday's crash was one of the worst rail disasters in India's history. Investigators said that a signaling failure might have been the cause of the disaster, in which a passenger train hit a freight train, derailing on the tracks before being hit by another passenger train coming in the opposite direction on a parallel track.

Read: ‘I am haunted by it’: Survivors of deadly train crash in India recount trauma

The collision involved two passenger trains, the Coromandel Express traveling from Howrah in West Bengal state to Chennai in Tamil Nadu state, and the Yesvantpur-Howrah Superfast Express traveling from Bengaluru in Karnataka to Howrah, officials said.

Many people had to make arduous journeys to reach the hospital.

At least 123 trains scheduled to pass through Odisha were either cancelled or delayed after the accident, Indian railways said Sunday. The disruption led air fares to Odisha to spike, prompting India’s civil aviation ministry to warn airlines over abnormal surges in pricing.

Usman Ansari, who came from Bihar to collect the body of his brother-in-law, Kasim Mia, said he took one train to Howrah in West Bengal state, and then another to Kharagpur, in the same state. From there he, along with two other friends, took a bus to the site of the crash, where they were told the bodies had been moved to Bhubaneswar.

The three of them rented a car to drive to the hospital, where Ansari was finally able to identify and collect his brother-in-law’s body after a 24-hour journey.

“Kasim used to say he wanted to do everything for his children,” he said, adding that compensation promised by the federal government would help take care of Kasim’s four young children.

Authorities recommended on Sunday that India’s Central Bureau of Investigations, which probes major criminal cases in the country, open an investigation into the crash.

Meanwhile Sunday evening, some train traffic was restored on the tracks where the crash happened, after two days of repair work in which hundreds of workers with excavators removed mangled debris of the trains.

The crash in Balasore occurred as Prime Minister Narendra Modi is focusing on the modernization of India's colonial-era railroad network.

The South Asian nation has one of the world’s most extensive and complicated railway systems with more than 40,000 miles (64,000 kilometers) of track, 14,000 passenger trains and 8,000 stations.

Read more: India train crash kills over 280, injures 900 in country's deadliest rail accident in decades

Spread across the country from the Himalayas in the north to tropical ports in the south, it has been weakened by decades of mismanagement and neglect. Despite efforts to improve safety, several hundred accidents happen every year.

Most train accidents are blamed on human error or outdated signaling equipment.

In August 1995, two trains collided near New Delhi, killing 358 people in one of India's worst-ever train accidents.

In 2016, a passenger train slid off the tracks between the cities of Indore and Patna, killing 146 people.

More than 22 million people ride trains across India every day.

Read more: India’s deadly train crash renews questions over safety as government pushes railway upgrade