Horrific moment overhead train collapses onto roadway, killing 19 and injuring at least 70 in Mexico (photos/video)

A metro train rail overpass in Mexico City collapsed as a train passed over it on Monday night spilling onto a crowded roadway below and killing at least 19 people while injuring 70.

According to Mexico City Mayor, Claudia Sheinbaum, a broken beam caused the accident which occured at about 10.30pm Monday, May 3, on the metro's Line 12 on the southeast side of the city.

Local Mexican channel Milenio TV posted a video showing the overpass collapsing on top of cars on a road five meters below the over pass.

According to the city's Comprehensive Risk Management and Civil Protection Agency, the accident left 19 dead with more still being counted.

Mayor Claudia Sheinbaum said on Twitter that 'firefighters, public safety personnel are working to salvage the situation.

Sheinbaum said that a broken beam caused the accident on Line 12 and that people were trapped in one of the cars. 'We don't know if they're alive,' she said.

As at press time, first responders are still searching through the wreckage for survivors.

The Mexico City Metro, one of the largest and busiest in the world, has had at least two serious accidents since its inauguration half a century ago.

Watch the video below.