At least 27 people were killed and thousands of residents forced to flee a central Mexican city on Sunday after a predawn pipeline explosion that may have been caused by oil thieves.
At least 52 others were injured and more than 100 homes damaged in what witnesses described as a series of blasts at a pumping station in San Martin Texmelucan.
The explosion flooded a stream with black crude and sparked "rivers of fire" in the streets, said Valentin Meneses, government secretary of the central state of Puebla.
Fires had been put out by early afternoon and the oil pipeline was closed down.
The state-run oil company, Petroleos Mexicanos, or Pemex, said the pumping station handled crude and the blast was possibly caused by thieves trying to tap into pipelines that are under high pressure.
The head of Pemex, Juan Jose Suarez, said the section of pipeline near where the blast occurred had been illegally tapped 60 times. He said there have been 550 cases of illegal tapping nationwide.
Pemex said it detected a sudden loss of pressure and then fires in two ducts. Meneses, the state official, said whoever attempted to tamper with the duct apparently lost control due to the high pressure. He said 32 houses were destroyed and 83 damaged by the explosion.
The oil company loses millions of dollars each year to theft of oil from its vast grid of pipelines by organized crime groups. The drug gang known as the Zetas is believed to have branched into oil theft as part of a diversification of its criminal enterprises.
President Felipe Calderon issued a statement promising to pursue any wrongdoers. Federal authorities have assumed responsibility for the investigation.
Although oil theft is common in Mexico, explosions are not.
Television images showed towering plumes of thick black smoke draping the town. Trees and dozens of cars were charred by flames erupting from the earth, sending smoke curling from manholes. A black sludge-like substance swirled in a stream.
People jumped into their cars and raced out of town. Civil protection officials urged residents to stay out of the 3-mile-wide disaster area.
"It was a catastrophe," resident Carlos Hipolito told Milenio Television after fleeing with about 60 relatives. He described seeing gas tanks exploding and flying through the air.