Mexican soldiers clean up debris at the Petroleos Mexicanos (Pemex) administrative building in Mexico City, Mexico, on Sunday, Feb. 3, 2013. The search for the cause of a blast that destroyed three floors of a building at Pemex' headquarters and killed at least 34 people entered a fourth day, as investigators toiled ahead of a self-imposed deadline for finding an answer. Photographer: Susana Gonzalez/Bloomberg via Getty Images
{"Image ImageDescription": "Mexican soldiers clean up debris at the Petroleos Mexicanos (Pemex) administrative building in Mexico City, Mexico, on Sunday, Feb. 3, 2013. The search for the cause of a blast that destroyed three floors of a building at Pemex' headquarters and killed at least 34 people entered a fourth day, as investigators toiled ahead of a self-imposed deadline for finding an answer. Photographer: Susana Gonzalez/Bloomberg via Getty Images", "Image Copyright": "2013 Bloomberg"}