MEXICO CITY — A blast that collapsed the lower floors of a building in the headquarters of Mexico's state-owned oil company, crushing at least 33 people, is being looked at as an accident although all lines of investigation remain open, the head of Petroleos Mexicanos said Friday.
As hundreds of emergency workers dug through the rubble, the company's worst disaster in a decade was fueling debate about the state of Pemex, which is suffering from decades of underinvestment and has been hit by a series of recent accidents.
Until now, virtually all the accidents had hit its petroleum infrastructure, not its office buildings. The blast on Thursday also injured 121 people.
"It seems like, from what one can observe, from what the experts are seeing, that it was an accident," Pemex director-general Emilio Lozoya told the Televisa network. "However no line of investigation will be discounted."
Early signs pointed to a problem in an area with electrical and air-conditioning equipment, according to a government official who was not authorized to speak by name.
A Pemex spokesman said the floors hit by the explosion housed administrative offices.