A passenger train derailed on Sunday in the Mexican state of Oaxaca, killing at least 13 people, according to Mexican authorities.

About 250 passengers and crew members were on board when the front engine derailed near the town of Nizanda, causing the train to partially fall down an embankment, media reported locals.

As of Sunday night, officials had not determined the cause. Authorities, including the federal prosecutor's office, said an investigation had been opened.

Rescue teams carried out efforts to reach the passengers, some of whom were trapped or fell down the slope. On Sunday night, the Secretary of the Navy reported that there were 98 injured, with 36 hospitalized.

President Claudia Sheinbaum wrote in X that five of the injured were in serious condition. He indicated that officials had been sent to the scene to support the families of those who had died.

The derailment occurred on Line Z of the Interoceanic Corridor of the Isthmus of Tehuantepec Railway, which runs about 290 kilometers from Salina Cruz, in the Pacific, to Coatzacoalcos, in the Gulf of Mexico.

Nizanda is located about 480 kilometers southeast of Mexico City, the capital.

On Sunday, those who feared their relatives had traveled on the derailed train were sharing their names and photos, along with pleas for help, on social media.

The Mexican government has described the rail route across the isthmus — the narrow land bridge between the Gulf of Mexico and the Pacific Ocean — as a vital artery for international trade. With ports and railway lines connecting the two bodies of water, some consider that it could compete with the Panama Canal.

During the term of former Mexican President Andrés Manuel López Obrador, the railway was renovated and expanded.

Along with the improvements intended for freight trains, the expansion included the incorporation of passenger service on the main route, Line Z, on which the train that ran derailed on Sunday. Passenger service officially began in late 2023.

Although other accidents have occurred on the railway, as of Sunday none had been fatal. While the line was being renovated, a freight train derailed, causing damage to infrastructure, but no injuries were reported.

About a week before Sunday's accident, a Line Z passenger train collided with a trailer in the southern state of Chiapas, but the nearly 150 passengers on board were unharmed. Authorities said the trailer had failed to yield.

Annie Correal is a Times reporter covering Mexico, Central America and the Caribbean.