A huge fire exploded at a pipeline leaking fuel in central Mexico on Friday, killing at least 21 people and badly burning 71 others.

The leak was caused by fuel thieves illegally tapping the pipeline in a small town in the state of Hidalgo, according to state oil company Petroleos Mexicanos, or Pemex.

Video footage showed dozens of residents near the town of Tlahuelilpan gathered to collect spilled fuel in buckets, garbage cans and other vessels.

'There was a report that residents were on the scene trying to obtain fuel,' according to a police report.

Two hours later, the pipeline burst into flames. The duct carries fuel, apparently gasoline, from the Gulf coast to the Mexico City area.

President Andrés Manuel López Obrador has declared an offensive against fuel theft, and on Friday he called on all branches of government to assist the victims.