MEXICO CITY (Reuters) - Mexican President Andres Manuel Lopez Obrador pledged to step up efforts to stamp out fuel theft on Saturday after an explosion at a pipeline killed at least 21 people and injured dozens more.

People react at the scene where a ruptured fuel pipeline exploded, in the municipality of Tlahuelilpan, Hidalgo, Mexico, near the Tula refinery of state oil firm Petroleos Mexicanos (Pemex), January 18, 2019 in this still image taken from a video obtained from social media. Veronica Monroy/Diario Plaza Juarez/via REUTERS

The blast at the pipeline, which was ruptured by suspected thieves, sent flames shooting into the skies in the municipality of Tlahuelilpan in the central state of Hidalgo on Friday.

Video footage showed residents scrambling to fill containers from the burst pipe and badly burned victims, raising questions about the management of an issue Lopez Obrador has made a top priority since taking office on Dec. 1.

Veteran leftist Lopez Obrador launched a crackdown on fuel theft on Dec. 27 and ordered pipelines to be closed temporarily to stop illegal taps draining billions of dollars from the heavily-indebted state oil firm Petroleos Mexicanos (Pemex).

“Far from stopping the fight ... against fuel theft, it’s going to become stronger, we’ll continue until we’ve eradicated these practices,” Lopez Obrador, who has said he will step up the security presence in sensitive areas, said.

Video on social media of people filling buckets from the pipeline during daylight hours in the presence of the armed forces prompting questions about why authorities had not acted.

The government said soldiers reached the scene after Pemex detected the illegal tap, but could not secure the area in time.

“At some point there were too many people there and the army and military personnel withdrew to avoid problems,” Public Security Minister Alfonso Durazo told broadcaster Televisa. “It was just as they were withdrawing that the explosion occurred.”

DEATH TOLL COULD RISE

Aerial footage on Mexican television showed what appeared to be smoldering corpses scattered on the ground near the blaze.

Hidalgo’s governor Omar Fayad said that emergency services had registered the charred bodies of 21 people, and that at least 71 others had been injured. However, he said the death toll could still rise as authorities reviewed the site.

Lopez Obrador says his shutdown greatly reduced theft, but it sparked fears for the economy, as well as triggering shortfalls in central Mexico, including Hidalgo.

Soon after the government said Friday’s blaze had been put out, TV footage showed tense exchanges between authorities guarding the site and residents arguing that the death toll was significantly higher than 21.

The damage also raised the prospect of a new setback in the government’s bid to restore fuel supply.

Pemex Chief Executive Officer Octavio Romero said the ruptured pipeline, which Durazo said early findings suggested had been tapped before, was vital to transporting an additive needed for gasoline produced in Mexico.