Mexico City — The death toll in the collapse of an elevated subway line in Mexico City on Tuesday (May 4) increased to 26 on Friday after an injured passenger died in hospital.

About 80 people were injured in the incident and 33 remain in hospital.

The US$1.3 billion (S$1.7 billion) Number 12 Line that collapsed was the newest section of a vast subway system that was opened in 1969.

There had been concerns about design problems and construction standards as well as allegations of corruption since the line was inaugurated in 2012.

CCTV footage showed the overpass collapsing as a train was travelling over it, sending up clouds of debris and sparks. The crash happened near the Olivos station, in the south-east of the city.

Elevated parts of the line, including the collapsed overpass, had to be closed for multiple repairs in 2014. Residents also reported cracks in the structure after an earthquake in 2017. The transport authorities made repairs following the reports.

The day after the crash, cranes were deployed to stabilise and remove the two train carriages that remained hanging from the structure.

According to an earlier bbc.com report, at least 79 people were injured, including one person who had been pulled out alive from a car underneath the wreckage. The mayor said the dead included children, but she did not give details.

Accompanied by officials involved in the construction and maintenance of the elevated metro line, President Andres Manuel Lopez Obrador said the investigation should be done quickly and nothing should be hidden from the public.

Officials added that investigations will be carried out by the federal attorney-general’s office, its Mexico City counterpart, and an external auditor, Norway’s DNV GL. /TISG