By ANTHONY HARRUP and LAURENCE ILIFF
MEXICO CITY -- A blast that ripped through an office block at the headquarters of Mexican state oil monopoly Petroleos Mexicanos, or Pemex, killing at least 37 people, was caused by an accumulation of gas, possibly methane, according to the preliminary results of the investigation, Mexican Attorney General Jesus Murillo said late Monday.
Speaking at a televised news conference, Mr. Murillo said there were no signs that last Thursday's explosion, which tore through several lower floors of a building next to Pemex's 48-story corporate tower in Mexico City, was caused by artificial explosives.
However, he stopped short of declaring the explosion an accident, and said the findings are still preliminary, adding that the source of the gas has yet to be determined.
Investigators are still working to determine where the gas came from, and whether or not there was anyone to blame.
The reasons for ruling out the use of explosives include the fact that there was no crater at the site of the blast, the steel girders weren't fractured, and the bodies of the victims weren't dismembered, he said. "There are no traces of explosives in the affected zone."
Only the bodies of three victims, workers who were in the area closest to the source of the blast, had suffered burns, he added.
Pemex's chief executive, Emilio Lozoya, said a woman who had been hospitalized with injuries died Monday, bringing the death toll to 37. Of 126 people treated for injuries, 29 remained hospitalized Monday, he said.
Mr. Lozoya also said Pemex staff would begin returning to the complex, including the Pemex tower, on Wednesday, after experts determined that the other buildings were safe.
Dow Jones Newswires