By Anthony Esposito

TLAHUELILPAN, Mexico (Reuters) - At least 66 people were killed after a pipeline ruptured by suspected fuel thieves exploded in central Mexico, authorities said on Saturday, as President Andres Manuel Lopez Obrador defended the army despite its failure to clear the site before the blast.

Forensic experts filled body bags with charred human remains in the field where the fiery blast occurred Friday evening by the town of Tlahuelilpan in the state of Hidalgo, in one of the deadliest incidents to hit Mexico’s troubled oil infrastructure in years.

Soldiers and other military personnel guarded the cordoned-off area that was littered with half-burned shoes, clothes and containers that were being used by people to collect fuel.

Grief-stricken family members blocked the dirt access road to the field, saying they would not let funeral service vehicles pass until they were told where the dead were being taken.

“They should give us an answer, if not, we’re not moving,” said Maria Isabel Garcia, 49, who was looking for two nieces. “They’ll have to drive the goddamn cars over us.”

The group eventually let the vehicles through.

ASSOCIATED PRESS Soldiers guard the area by an oil pipeline explosion in Tlahuelilpan, Hidalgo state.

At a news conference with Lopez Obrador, Hidalgo State Governor Omar Fayad said 66 people were killed and 76 people injured in the explosion, which happened as local residents scrambled to fill buckets and drums from a gush of fuel from the pipeline that authorities said rose up to 23 feet (7 meters) high.

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).

Video on social media showed people filling buckets from the pipeline during daylight hours in the presence of the armed forces before the blast. But Lopez Obrador, who vowed to continue the crackdown on fuel theft, defended the army in the face of questions about why soldiers failed to prevent the tragedy.

“We’re not going to fight fire with fire,” he said. “We think that people are good, honest, and if we’ve reached these extremes ... it’s because they were abandoned.”

Lopez Obrador said the army had been right to avoid a confrontation due to the large number of people seeking to make off with a trove of free fuel - a few liters of which are worth more than the daily minimum wage in Mexico.

Blaming previous governments for neglecting the population, he said fuel theft had been a chronic problem for years and that the priority was to eradicate the social problems and lack of opportunities that had made people put their lives at risk.

Still, Lopez Obrador had vowed to tighten security in sensitive sections of the oil infrastructure, and the ruptured pipeline was only a few miles away from a major oil refinery.

ASSOCIATED PRESS Staff of Pemex, Petroleos Mexicanos, works the area of a oil pipeline explosion in Tlahuelilpan, Hidalgo state.

Pemex’s Chief Executive Octavio Romero told reporters that there had been 10 illegal fuel taps in the same municipality in the last three months alone. Neither he nor the president said exactly when the valves to the pipeline were closed.

Relatives of victims stood huddled together, some of them crying, after the massive blast. Much of the rush to siphon off fuel and the chaos of the explosion was captured on mobile phones and began quickly circulating on social media.

Local media published graphic pictures of victims from the blast site covered in burns and shorn of their clothes.

Lopez Obrador has said his decision to shut down pipelines to combat crime has greatly reduced fuel theft. However, it sparked fears for the economy, as well as triggering fuel shortfalls in central Mexico, including Hidalgo.

“There was a gasoline shortage, people one way or another wanted to be able to move around,” said farmer Ernesto Sierra, 44. “Some even came with their bean pots.”

(Reporting by Anthony Esposito; Writing by Dave Graham and Christine Murray; Editing by Alexander Smith and Tom Brown)