Perez recalls telling his son: "Let's go ... this thing is going to explode."
And it did, with a fireball that engulfed locals scooping up the spilling gasoline and underscored the dangers of an epidemic of fuel theft from pipelines that Mexico's new president has vowed to fight.
By Saturday evening the death toll from Friday's blaze had risen to 73, with another 74 people injured and dozens more were missing.
Perez and his son escaped the flames. On Saturday, he returned to the scorched field in the town of Tlahuelilpan in Hidalgo state to look for missing friends. It was a fruitless task. Only a handful of the remains still had skin. Dozens were burned to the bone or to ash when the gusher of gasoline exploded.
Just a few feet from where the pipeline passed through an alfalfa field, the dead seem to have fallen in heaps, perhaps as they stumbled over each other or tried to help one another as the geyser of gasoline turned to flames.
On Friday, hundreds of people had gathered in an almost festive atmosphere in a field where the duct had been perforated by fuel thieves and gasoline spewed 20 feet into the air.
State oil company Petroleos Mexicanos, or Pemex, said the pipeline, which supplies much of central Mexico with fuel, had just reopened after being shut since Dec. 23 and that it had been breached 10 times over three months.
The tragedy came just three weeks after President Andres Manuel Lopez Obrador launched an offensive against fuel theft gangs that have drilled dangerous, illegal taps into pipelines an astounding 12,581 times in the first 10 months of 2018, an average of about 42 per day. The crackdown has led to widespread fuel shortages at gas stations throughout the country as Pemex deviates distribution, both licit and illicit.
Lopez Obrador vowed on Saturday to continue the fight against a practice that steals about $3 billion per year in fuel.
He said the attorney general's office will investigate whether the explosion was intentional — caused by an individual or group — or whether the fireball occurred due to the inherent risk of clandestine fuel extraction. He called on townspeople to give testimony not only about Friday's events in Hidalgo, but about the entire black-market chain of fuel theft.
"I believe in the people, I trust in the people, and I know that with these painful, regrettable lessons, the people will also distance themselves from these practices," he said.
Lopez Obrador faces an uphill fight against a practice that locals say is deeply rooted in the poor rural areas where pipelines pass, covered by only a foot or two of dirt. In some cases, locals support the fuel thieves.
Tlahuelilpan, population 20,000, is just 8 miles (13 kilometers) from Pemex's Tula refinery. Pemex Chief Executive Octavio Romero said an estimated 10,000 barrels of premium gasoline were rushing through the pipeline with 20 kilograms of pressure when it was ruptured.
Locals on Saturday expressed both sympathy and consternation toward the president's war on fuel gangs.
Arely Calva Martinez said the recent shortages at gas stations raised the temptation to salvage fuel from the gusher.
Her brother Marco Alfredo, a teacher, was desperate for gas to drive 90 minutes back and forth to work when word spread via Facebook that fuel spewing into the field. Marco Alfredo and another brother, Yonathan, were in the field when the fire erupted. They haven't been seen since.
"I think if there had been gas in the gas stations, many of these people wouldn't have been here," Calva Martinez said while holding a picture of her brothers.
Tears streamed down Erica Bautista's cheeks as she held up her cellphone with pictures of her brother, Valentin Hernandez Cornejo, 24, a taxi driver, and his wife, Yesica, both of whom are also missing. Valentin faced "enormous lines" for a limited ration of gas, she said. Then he received a phone call alerting him to the fuel spill.
"We want to at least find a cadaver," she said while weeping.
Health officials were taking DNA samples from direct relatives at the local community center in Tlahuelilpan to aid in identification. Outside, a long, chilling list of the missing was taped to a window.
Wrapped in a blanket, Hugo Olvera Estrada said he had gone to six nearby hospitals looking for his 13-year-old son, who had joined the crowd at the fuel spill. He hasn't been seen since.
"Ay, no, where is my son?" he wailed.
Lopez Obrador launched the offensive against illegal taps soon after taking office Dec. 1, deploying 3,200 marines to guard pipelines and refineries. His administration also shut down pipelines to detect and deter illegal taps, relying more on delivering fuel by tanker truck.
Mexican Defense Secretary Luis Cresencio said there are 50 soldiers stationed every 12 miles along the pipelines, and that they patrol 24 hours a day. But the soldiers have been ordered not to engage with fuel thieves out of fear that an escalation could result in more shootings of unarmed civilians or more soldiers being beaten by a mob.
"We don't want this sort of confrontation," Cresencio said.
A second pipeline burst into flames Friday in the neighboring state of Queretaro as a result of another illegal tap. But in this fire there were no reported casualties.
In December 2010, authorities also blamed thieves for a pipeline explosion in a central Mexico near the capital that killed 28 people, including 13 children.
Associated Press writer Amy Guthrie contributed to this story from Mexico City.