At least 23 people have been killed and dozens injured after a metro overpass collapsed in Mexico City while a train was traveling on it, officials say.

Several train carriages plunged to the ground, crushing at least one car, which was on a busy road underneath.

Children are among the dead. Rescue workers and firefighters are still searching for survivors.

Dramatic footage has emerged showing the overpass collapsing at the Olivos station on the metro’s Line 12.

Mexico City Mayor Claudia Sheinbaum said the cause of the accident was still being investigated, but it appeared a girder had given way on the overpass.

One person trapped in a car underneath the collapsed structure had been pulled out alive and taken to hospital, she said. At least 65 people were injured, and seven were in a serious condition.

Residents had reported cracks in the structure after a deadly 2017 earthquake, according to local media. Mexico’s El Universal newspaper says transport authorities made repairs following the reports.

The accident happened at around 22:00 local time on Monday (03:00 GMT). A crane was sent to the scene to stabilize the carriages amid concerns they could fall onto the road.

“We only heard a loud thunder, and everything fell apart,” 26-year-old Mariana, who survived the crash, told El Universal.

“There were many people standing and sitting in the carriage, and when the carriage fell, we went flying and hit our heads on its roof,” she described the moment of the accident.

She also said that she and other passengers were trapped among the carriage’s twisted metal before they managed to escape through a window.

One eyewitness told Mexico’s Televisa TV network: “Suddenly I saw that the structure was shaking.”

“When the dust cleared we ran… to see if we could help. There were no screams. I don’t know if they were in shock,” the witness said.