Mexico - Blast Caused by Methane Gas, Report Says - NYTimes.com The Mexican attorney general's office said Friday that methane gas combined with vapors emitted by solvents caused the deadly explosion at the headquarters of Mexico's state-owned oil monopoly, Petróleos Mexicanos, or Pemex, on Jan. 31. The basement blast killed 37 people and injured more than 120 others. In a statement summarizing the results of its investigation, the attorney general's office said that hydrocarbons that had leaked into the ground decades before the building was constructed had contributed to the buildup of methane gas and that an electrical spark had probably ignited the combustible mix. Pemex is suffering from declining production and has long had a poor safety record. President Enrique Peña Nieto has said he hopes to win approval from Mexico's Congress to open up the company to private investment before the end of the year.