Petroleos Mexicanos workers talk about the debris at the Pemex... News PhotoAdministrator,Emergencies and Disasters,Exploding,Finance,Fuel and Power Generation,Horizontal,Mexico,Mexico City,North America,Occupation,Petrol,Petroleos Mexicanos,Security,Talking,The Americas,The Media,USAPhotographer Collection: Bloomberg 2013 BloombergPetroleos Mexicanos (Pemex) workers talk about the debris at the 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