MEXICO CITY (AP) — A gas tanker truck exploded and burned multiple vehicles under a Mexico City highway overpass Wednesday, killing three people and injuring 70 others, some with their entire bodies charred and others waiting for help in the road with burns and torn clothing.

The crash of the truck carrying more than 13,000 gallons (49,500 liters) of gasoline on a major highway sent flames and smoke billowing over the south of the capital.

Mayor Clara Brugada called the explosion an “emergency” that burned nearly 30 vehicles and left 19 of those injured in grave condition, including the driver of the truck. Among those injured were a baby and a 2-year-old child.

Brugada said prosecutors were investigating, but it appeared that the truck exploded after it tipped over on the highway.

“This is a horrible accident,” the mayor said at the site of the explosion.

The gas tanker laying on its side had the logo of the energy business Silza on its side, but in a call with The Associated Press a company official who did not want to be identified denied it was their vehicle. The company did not immediately respond to an email requesting for comment or more details.

Later in the night, Mexico’s environmental ministry said in a statement that Silza didn’t have updated insurance paperwork required to transport gas because it’s application was rejected.

Images circulated online by authorities showed a mass of flames mushrooming from a truck. Others on social media show dozens of people screaming and running from the explosion.

People whose entire bodies appeared to have been burned, some with tattered clothing melded onto skin, emerged from the flames. Others in the images had burned-off faces.

As emergency vehicles sped by and medics attended to the wounded, groups of neighbors ran helped pull burn victims from the fire and get them to safety.

Lists of those injured showed some had up to 100% of their skin burned off.

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.

After fire teams snuffed out the flames with hoses and foam, Mexico City officials announced the flames were “completely under control.”

The explosion occurred on one of the most important roadways flowing out of the capital on the way to the city of Puebla. The roadway was reopened by evening.