MEXICO CITY, Sept 14, 2025 (BSS/AFP) - The death toll from the explosion of a gas truck in Mexico City at mid-week has risen to 13, the mayor's office said Saturday.

Several people suffered second- and third-degree burns when a truck carrying almost 50,000 liters of gas suddenly blew up Wednesday in the densely populated district of Iztapalapa.

Initial reports said three people were killed and dozens injured, but the death toll has ticked up since then.

Forty injured people were still being treated Saturday in hospitals around the city, according to the latest official figures.

Among the latest fatalities was Alicia Matias, 49, whom the Mexican press had dubbed "the hero grandma" because she protected her two-year-old granddaughter with her body during the explosion.

One of the most devastating images coming out of the tragedy was of Matias carrying the girl in her arms looking for help, despite having suffered burns on 90 percent of her body.

"Her act of love has left a profound mark," Mexico City Mayor Clara Brugada wrote Saturday on X.

Investigators say the accident likely occurred because the truck was driving too fast, and may have hit an object that punctured the tank.

Brugada said her government will seek to impose new regulations on fuel tank trucks as they travel through the city of 9.2 million residents to avoid such accidents in the future.