Updated May 4, 2021 at 8:50 AM ET

An elevated train derailed in Mexico City after a concrete overpass it was crossing collapsed Monday night. At least 23 people were killed and nearly 80 were injured and transferred to nearby hospitals, according to government officials.

Photos posted online show two train cars dangling precariously from the elevated track. The yellow and orange cars were crushed together as the overpass collapsed, leaving them suspended at a V-shaped angle.

Given the tenuous position of the wreckage, a search for possible trapped survivors had to be suspended due to safety concerns. A crane was brought in to help stabilize the site for emergency responders.

"We don't know if they are alive," Mexico City Mayor Claudia Sheinbaum said of people who might still be trapped inside.

In a tweet, Sheinbaum said 23 people were killed. She said some children were among the dead and that seven of the injured were in serious condition and undergoing surgery, according to The Associated Press. The Secretariat for Comprehensive Risk Management and Civil Protection of Mexico City tweeted a list of 79 people hospitalized.

Four bodies trapped inside a rail car suspended from the overpass could not be immediately recovered. It wasn't clear whether they were among the 23 listed as dead, AP reports.

La Jornada newspaper reported the crash occurred at roughly 10:25 p.m. (11:25 p.m. ET).

Sheinbaum continued to update the public throughout the night and early morning following the crash. The death toll continued to rise overnight.

The derailment occurred on Line 12 of the subway system at Olivos Station, in the borough of Tlahuac, according to Mexico's civil protection agency. Shortly after the crash, Mexico City's metro service warned the public to stay away from the area.

Line 12, which runs through the city's south side and is the newest branch of the system, will remain closed as emergency responders work in the crash site, likely slowing down one of the world's busiest metro systems.

Sheinbaum said on social media that a full structural review of the entire subway line and investigation into the cause of the crash will be ordered.

The AP reports that the collapse could have repercussions for Foreign Relations Secretary Marcelo Ebrard. Line 12 was built while he was mayor of Mexico City from 2006 to 2012. After he left office, the project was criticized for poor design and construction. It was partly closed in 2013 for track repair.

On Twitter, Ebrard called the collapse a "tragedy" and said he is "entirely at the disposition of authorities to contribute in whatever way is necessary."

The city's subway system was the site of another crash in March 2020. Two trains collided, killing one man and injuring 41 people, according to the AP.

La Jornada quoted Mexico's secretary of public security, Omar Garcia Harfuch, as urging people to "not speculate" about the cause of the collapse. "Let's wait for the expert opinions," Harfuch said.

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