The concrete subway overpass partially collapsed, and images and videos from the scene showed parts of a train hanging in mid-air for hours. Some 49 have been hospitalised.
A rescue operation is under way, the government said but that was suspended early on Tuesday, however, because of safety concerns for those working near the precariously dangling car.
A crane was brought in to help shore it up. “We don’t know if they are alive,” Mayor Claudia Sheinbaum said of the people possibly trapped inside the car. Government officials later said that four of the victims’ bodies were still trapped in the wreckage.
By Tuesday afternoon, only five of the dead had been identified, Ms Sheinbaum said at a news conference, as she increased the number of known victims from the 23 announced in the morning.
A video captured by an onlooker shows the parts of the train falling on cars below the overpass on the road.
On Twitter, Ms Sheinbaum wrote: “Unfortunately, there are dead and injured people. I am on-site supporting the installation of the command centre.”
Several local TV channels are showing footage of chaos at the accident site, with crews searching for survivors. Videos on Mexican TV and social media showed train cars hanging and sirens blaring in the neighbourhood. On Milenio TV, firefighters and emergency workers were seen helping the survivors.
The crash occurred at 10.25pm on Monday night. La Jornada reported that the injured have been taken to several hospitals.
Mexico’s civil protection agency said on Twitter that the derailment occurred on Line 12 of the subway system at Olivos Station in southeast Mexico City.
Marcelo Ebrard, secretary of foreign relations, tweeted: “What happened today in the Metro is a terrible tragedy. My solidarity with the victims and their families. Of course, causes must be investigated and responsibilities defined. I reiterate myself at the entire disposal of the authorities to contribute in whatever is necessary.”
Olga Sánchez Cordero, head of the ministry of the Interior, said on social media that investigations into the train accident must be carried out. She tweeted: “Solidarity and fraternity with the families affected by the tragedy tonight in the Metro and our support for the government of Mexico City. Investigations must be carried out and those responsible be determined as soon as possible. I will be very attentive to whatever is required.”
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies