A full investigation will be carried out into the causes of an overpass collapse that killed at least 24 people when one of Mexico City’s iconic orange metro trains plunged onto a busy road below, the city’s mayor Claudia Sheinbaum has said.

Two train carriages precariously hung from the damaged overpass after the accident late on Monday, and rescue efforts were suspended with authorities worried that more train parts and debris could slam down onto the road.

Sheinbaum said it was too soon to say who was responsible for what happened.

Speaking alongside Sheinbaum and other senior officials at a news conference, Mexican President Andres Manuel Lopez Obrador said that the investigation should be done quickly and nothing hidden from the Mexican people.

“A thorough investigation will be carried out … to know the truth,” Lopez Obrador said.

“From that, the responsibility will be established,” he added.

Foreign Minister Marcelo Ebrard, who was city mayor when the overpass was built, added that it was the most “terrible” accident to have hit the local transport system, and that he was ready to cooperate with authorities in the investigation.

“I share the indignation that exists,” he said.

Search for missing continues

Video of the collapse showed the structure plummeting onto a stream of cars near Olivos station in the southeast of the city at about 10:30pm local time (03:30 GMT on Tuesday), sending up clouds of dust and rubble.

Sheinbaum said one person had been pulled alive from a car that was trapped on the road below, adding that 49 of the injured were hospitalised, and that seven were in a serious condition and undergoing surgery.

She said children were among the dead.

The overpass was about five metres (16 feet) above the road in the borough of Tlahuac, but the train ran above a concrete median strip, which apparently lessened the casualties among motorists on the road below.

On Tuesday, family members continued to search for their loved ones.

Cristian Segura Osorio told the Associated Press he had visited three hospitals searching for his sister Angelica Segura Osorio, who he believes would have been travelling on the metro carriage when the incident took place.

He said the mother of two was not answering calls to her cell phone or WhatsApp messages. She also does not appear in the patient list of several hospitals where they have searched for her.

“If someone has seen her or knows anything, please help us,” Segura Osorio said, as he showed a photo of his missing sister wearing a yellow and black uniform.