President Felipe Calderón toured the disaster area left by pipeline explosion that ravaged this small city and vowed to bring those responsible to justice.
The blast killed at least 28 people, including 13 children. Dozens were injured, too.
Calderón talked to displaced people in San Martín Texmelucan and visited injured victims in a hospital. Interior Minister Francisco Blake Mora mobilized several federal ministries to help victims with medical care, shelter and recovering their lost homes and property.
Authorities said the explosion was apparently caused by thieves trying to steal crude oil, and local, state and federal agencies promised to stop at nothing to bring whoever is responsible to justice. There were no immediate arrests.
The blast initially estimated to have affected 5,000 residents in a three-mile (five-kilometer) radius, left metal and pavement twisted and in some cases burned to ash in the intense heat.
Zoyla Pérez was among those affected. She awoke before dawn to a strange, overpowering smell, like gasoline.
Outside the ground looked as if it were flowing in tar, as crude gushing from a pipeline rushed down the street and into a river. Suddenly flames leapt skyward as a massive explosion laid waste to parts of this city in central Mexico, incinerating people, cars, houses and trees.
"It was like we were living in an inferno," said Perez, 27. "Everything was covered in smoke."
San Martin Texmelucan is a city of about 130,000 people, according to 2005 government figures, in view of Central Mexico's spectacular volcanos, Popocatepetl and Iztaccihuatl. Farming is important to the area's economy, along with a manufacturing sector that makes chemical and petrochemical products, pharmaceuticals, textiles and metals, the city's Web site says.
State-owned oil company Petroleos Mexicanos, or Pemex, said in a statement that it had shut down the pipeline.
Pemex has struggled with chronic theft, losing as much as 10 percent of all of its product. Criminals tap remote pipelines, sometimes building pipelines of their own, to siphon off hundreds of millions of dollars' worth of oil each year, Pemex has said.
There have been 100 such illegal taps this year all along the pipeline that exploded Sunday. It runs from Veracruz, a heavy oil-producing Gulf coast state, to Mexico state outside the capital, said Juan Jose Suarez, Pemex director general.
Officials believe bandits were at it again when the blast occurred. Investigators found a hole in the pipeline and equipment for extracting crude, said Laura Gurza, chief of the federal Civil Protection emergency response agency.
Thieves "lost control because of the high pressure with which the fuel exits the pipeline," said Valentín Meneses, interior secretary for the state of Puebla, where San Martín is located.
Several dead bodies were found in cars near the location of the leak, but authorities didn't know if they were involved in the theft or there by coincidence.
Based on reporting by the Associated Press.