Mexican authorities now say at least 79 people were killed in Friday night's fuel pipeline blast.
It is believed the explosion occurred after the line was ruptured by suspected fuel thieves in the town of Tlahuelilpan, in Hidalgo state.
Officials say scores of people had been scrambling to fill up containers and were engulfed in an inferno.
Dozens of charred bodies remain at the scene, which is cordoned off by security forces.
Hidalgo state governor Omar Fayad said 74 people had been hospitalised after the blast.
Locals said President Andrés Manuel López Obrador's new policy to crack down on fuel theft had created shortages.
"Everyone came to see if they could get a bit of gasoline for their car," farmer Isaias García told Reuters news agency. "There isn't any in petrol stations."
Distraught relatives have continued to gather at site of the explosion.
Forensic experts have been photographing remains amid a backdrop of burned clothing and discarded fuel buckets.
A few litres of fuel are worth more than the daily minimum wage in Mexico.
What exactly happened on Friday?
Pemex, Mexico's state-owned petroleum company, said the fire had been caused by illegal tapping.
It is believed thieves drilled through the Tula-Tuxpan pipeline - just a few miles away from a large refinery - causing a large jet of gasoline to rise into the air.
Mexican officials say up to 800 people, seeing the gasoline geyser, then flocked around it to fill up containers. It erupted into flame a couple of hours later.
At a press conference, Pemex chief executive Octavio Romero said the firm had been aware of a leak along the pipeline at 16:50 local time.
Mr Romero said a valve had been closed to stem the leak, but he did not say what time it was shut.
The pipeline has been closed since late December because of repeated hits by gangs. Since reopening on 16 January, it has been targeted four more times, according to Pemex.
Some locals criticised security forces at the scene for not warning people more forcibly to get away from the leaking fuel.
But President López Obrador defended the army against criticism, saying only 25 soldiers were present and villagers ignored warnings not to get close.
He also avoided criticising the people, saying if they had to resort to "extremes" by stealing fuel "it's because they were abandoned".
President López Obrador added that, even if the pipeline had been sealed immediately after the leak, 10,000 barrels-worth of gasoline would have still been trapped in the section of pipeline between Tlahuelilpan and the nearby refinery.
Prosecutors will be investigating the incident.
What is the fuel theft problem?
Fuel theft, known locally as "huachicoleo" (or moonshining) is rampant in some Mexican communities.
The government has said the practice cost the country about $3bn (£2.3bn) last year.
President López Obrador, who took office in December, has launched a major crackdown. Thousands of marines have been deployed to guard pipelines, some of which have been shut down altogether in places.
The policy has led to increased reliance on tanker deliveries and there have been widespread reports of long lines at petrol stations.
After the blast, Mr Fayad issued a plea on Twitter to try to avoid further disasters.
"I urge the entire population not to be complicit in fuel theft," Mr Fayad posted (in Spanish). "Apart from being illegal, it puts your life and those of your families at risk. What happened today in Tlahuelilpan should not be repeated."
President López Obrador vowed to press on with his anti-theft policy until it was eradicated.
"Rather than stopping the strategy, the fight against the illegality and theft of fuel, it will be strengthened," he told reporters.
Pemex has suffered a number of other deadly accidents in the past.
At least 37 people were killed in an explosion at its Mexico City headquarters in 2013 and another 26 died in a fire at a gas facility in 2012.