At least 21 people were killed and 71 injured when a pipeline that was sabotaged by suspected burglars in central Mexico exploded, authorities said.
Mexican television footage of the flames was heightened by a pipeline explosion in the municipality of Tallahulban in the state of Hidalgo, north of Mexico City, and people were shouting and yelling for help.
"There is still a very hot area and we believe that the number of casualties or deaths in that area, which we have not been able to reach, could rise," Hidalgo governor Omar Fayyad told Mexican television.
"I call on everyone not to get involved in the theft of fuel, regardless of the fact that this work is illegal, it puts your life and the life of your family at risk."
Other television footage showed on Friday people burned by the blast as the government sent ambulances and doctors to treat the injured.
The flow of fuel from the pipeline and the presence of dozens of people at the site are also trying to fill plastic containers and containers with fuel.
This is the worst accident of recent history in Mexico, where the oil and gas pipeline network has been subjected to hundreds of sabotage operations for theft.
Mexican President Andres Manuel Lopez Obrador has launched a major campaign to stamp out the fuel-theft outbreak, which the government said cost the country more than $ 3 billion last year.
The campaign enjoys broad public support, although the president's decision to close pipelines to prevent theft has caused a major disruption to fuel supplies in central Mexico.