Three people died and 67 were wounded when a gas truck exploded in Mexico City, causing widespread damage, municipal officials said.

The vehicle blew up on a bridge in the densely populated Iztapalapa district in the capital's east on Wednesday, leaving 19 people with second- and third-degree burns, Mexico City Mayor Clara Brugada said.

She later announced that three people had died and 67 injured people were being treated in area hospitals, including several children.

Images distributed on television and social networks show the moment of the powerful explosion.

People can be seen with what appear to be serious burns, while others near the disaster zone flee fast-spreading flames that were later brought under control by firefighters.

Several other vehicles were damaged in the explosion, the causes of which are not yet known.

Images showed the burning truck, which was transporting 49,500 litres of gas, overturned on the road.

The smoke from the inferno reached a nearby trolleybus station, one of the main modes of transport in the city of 9.2 million inhabitants.

Iztapalapa, home to 1.8 million, is one of the most populated districts in the country.

Mexico is no stranger to disasters linked to fuel trucks and hydrocarbon infrastructure.

The worst occurred in January 2019, when a fire and subsequent explosion on a pipeline being looted killed 137 people in the town of Tlahuelilpan, in the central state of Hidalgo. (AFP)