MEXICAN investigators are working to determine the cause of a crash in which a tanker truck carrying more than 13,000 gallons of gas exploded on a major highway in the capital, killing at least four people and injuring 90.

Wednesday’s fiery crash, which burned more than two dozen vehicles, created a gruesome scene of badly burned survivors staggering in the street in tattered clothing as first responders rushed to the scene. 

The injured suffered second and third-degree burns.

While Wednesday’s accident involved a large tanker, rather than the smaller ones that make residential deliveries, both have been involved in deadly crashes over the past decade.

The crash occurred on the road connecting Mexico City with Puebla and in the capital’s most populous borough, Iztapalapa.

The gas tanker laying on its side had the logo of the energy business Silza on its side, but the company did not immediately respond to a request for comment or more details.

Later on Wednesday, the federal agency charged with regulating industrial safety in the hydrocarbon sector said in a statement that Silza didn’t have updated insurance paperwork required to transport gas.

Mexican President Claudia Sheinbaum expressed her condolences to families of those who died in a post on X and thanked emergency teams for their work.