The death toll from the collapse of an overpass on the Mexico City metro rose to 24 on Tuesday as crews untangled train carriages from the steel and concrete wreckage that fell onto a road beneath.

Another 77 people were injured when the support beams collapsed at about 10:30pm on Monday as a train passed along the elevated section, said Mayor Claudia Sheinbaum in describing one of the deadliest incidents in the history of the subway system, one of the world’s busiest.

On Tuesday, a crane carefully lowered a train car containing four bodies to the ground.

Of the 24 killed, 21 died at the scene, while the others died at hospitals. Children were among the fatalities, Ms Sheinbaum said.

Mexican Foreign Relations Secretary Marcelo Ebrard called the collapse “the most terrible accident we have ever had in mass transportation.”

Mr Ebrard was Mexico City’s mayor from 2006 to 2012, when the affected line was built.

“The cause of the collapse of the beam must be established through an expert investigation,” Ms Sheinbaum said.

The overpass was about five metres above the road in the borough of Tlahuac, but the train ran above a concrete median strip, which apparently lessened the casualties among motorists.

The Mexico City Metro — which is among the world’s cheapest with tickets costing about 25 cents — has had at least three serious accidents since its inauguration half a century ago.

In March 2020, a collision between two trains at the Tacubaya station left one passenger dead and injured 41. In 2015, a train that did not stop on time crashed into another at the Oceania station, injuring 12.

In October 1975, at least 26 people were killed in a metro accident.

Hundreds of police officers and firefighters cordoned off the scene as desperate friends and relatives of people believed to be on the train gathered.

Despite the fact that the coronavirus situation remains serious in Mexico City, they crowded together waiting for news.

The collapse occurred on Line 12, the subway’s newest. It stretches far into the city’s south side. Like many of the dozen subway lines, it runs underground through more central areas of the city of nine million but is on elevated concrete structures on the outskirts.

Allegations of poor design and construction on the subway line emerged soon after Mr Ebrard left office as mayor. The line had to be partly closed in 2013 so tracks could be repaired.

PA Media