Two passenger trains collided around 7 p.m. local time Friday after one of them struck a stationary freight train at full speed and derailed in the Balasore District of Odisha State, according to an initial government report. At least 275 people were killed, according to the state government on Sunday, revising an earlier death toll of 288 after an official said that some victims had been counted twice. More than 1,100 passengers were injured.

In a preliminary assessment, officials say the disaster began when the first of the two passenger trains struck the idled freight train at full speed, and then derailed. A second passenger train, heading in the opposite direction, then struck some of the dislocated cars. Officials are focusing on signal problems as the probable cause.

More than 2,200 passengers in all were onboard the passenger trains, according to railway officials, and at least 23 cars were derailed. The force of the collision left cars so mangled that rescuers used cutting equipment to reach victims.

One of the trains was a Shalimar-Chennai Coromandel Express train, according to South Eastern Railway. The Coromandel Express service connects the biggest cities on India’s east coast at a relatively high speed. The other passenger train was a Yesvantpur-Howrah Superfast Express train, running from a commuter hub in the southern city of Bengaluru to Kolkata, the capital of the northeastern state of West Bengal.

India’s railway minister, Ashwini Vaishnaw, said that he had ordered an investigation into the cause and that those affected by the crash would receive compensation.

The train derailed near Balasore.

The crash occurred at the Bahanaga Bazar station near Balasore, a city near the coast in the northeastern state of Odisha. The area is known for its ancient temples and history as a 17th-century British trading post.

Balasore is several hours by car to the nearest airport, in Bhubaneswar, Odisha’s capital. May is usually the hottest time of year, and daily temperatures reached about 100 degrees in the days before the crash.

The rescue operation was over by Saturday. Dozens of trains had been canceled, but crews were rushing to restore service after pushing rail cars involved in the crash off the tracks. Mr. Vaishnaw has said that he expects service to resume by Wednesday at the latest. But the delays meant that families of the victims were still struggling to reach the crash site on Sunday, and many bodies remain unclaimed, according to local officials and doctors.

Derailments have become less common.

Often referred to as being crucial to India’s economy, the country’s vast rail network is one of the world’s largest, and is central to lives and livelihoods, particularly in more rural pockets. Nearly all of India’s rail lines, 98 percent, were built from 1870 to 1930, according to a 2018 study published in The American Economic Review.

The deadliest accident in the history of Indian rail is believed to have been in 1981, when a passenger train derailed as it was crossing a bridge in the state of Bihar. Its cars sank into the Bagmati River, killing an estimated 750 passengers; many bodies were never recovered.

Derailments were once frequent in India, with an average of 475 per year from 1980 to about the turn of the century. They have become much less common, with an average of just over 50 a year in the decade leading up to 2021, according to a paper by railway officials presented at the World Congress on Disaster Management.

Rail safety more generally has improved in recent years, with the total number of serious train accidents dropping steadily to 22 in the 2020 fiscal year, from more than 300 annually two decades ago. By 2020, for two years in a row, India had recorded no passenger deaths in rail accidents — a milestone hailed by the government of Prime Minister Narendra Modi. Until 2017, more than 100 passengers were killed every year.

Even so, deadly crashes have persisted. In 2016, 14 train cars derailed in India’s northeast in the middle of the night, killing more than 140 passengers and injuring 200 others. Officials at the time said a “fracture” in the tracks might have been responsible. In 2017, a late-night derailment in southern India killed at least 36 passengers and injured 40 others.

The crash on Friday was the deadliest at least since a collision in 1995 about 125 miles from Delhi that killed more than 350 people.

Modi has made improving transit a priority.

A main reason for the improved safety of the trains was the elimination of thousands of unsupervised railway crossings, which Mr. Modi’s government said had been achieved in 2019. The relatively low-level engineering work of building underpasses and posting more signal conductors also drastically reduced crashes.

Mr. Modi has made it a priority to improve infrastructure, especially transportation systems, around the country. In recent years, the railroads, among the most visible projects for ordinary citizens, have received attention for a series of high-tech initiatives. Mr. Modi has been inaugurating electric medium-range trains and is building a Japanese-style “bullet train” corridor on the west coast to connect Mumbai with Ahmedabad.

On Saturday, though, instead of inaugurating a new train as scheduled, Mr. Modi visited the scene of the train wreck.

The train system, and especially train accidents, have long affected the fortunes of India’s politicians. The cabinet position of railway minister has been one of the most sought-after posts because it is both high-profile and influential in business and industry. Suresh Prabhu, who is credited with designing New Delhi’s world-class subway system, was pressed into resigning from his post in September 2017, after a series of accidents.

Within hours of Friday’s disaster, some opposition politicians were already calling for the resignation of Mr. Vaishnaw.

Mujib Mashal contributed reporting.