Mexico City oil company explosion

The Mexican government said on Feb. 4 that a gas leak caused a blast that killed at least 37 people at the offices of state oil monopoly Pemex in Mexico City, raising fresh questions about the firm's safety record.

Rescue workers and firefighters carry an injured person after an explosion in a building at Mexico's state-owned oil company PEMEX complex, in Mexico City, Thursday Jan. 31, 2013. The explosion killed more than 10 people and injured some 80 as it heavily damaged three floors of the building. According to civil protection and local media some people remained trapped in the debris from the explosion, which occurred in the basement of an administrative building next to the iconic, 52-story tower of Petroleos Mexicanos, or PEMEX. (AP Photo/Eduardo Verdugo)

Firefighters belonging to the Tacubaya sector and emergency responders pull out a survivor after an explosion at an adjacent building to the executive tower of Mexico's state-owned oil company PEMEX, in Mexico City, Thursday Jan. 31, 2013. A large explosion occurred in the lower floors of the building and dozens have been reported injured so far. (AP Photo/Guillermo Gutierrez)

Firefighters belonging to the Tacubaya sector and workers dig for survivors after an explosion at an adjacent building to the executive tower of Mexico's state-owned oil company PEMEX, in Mexico City, Thursday Jan. 31, 2013. A large explosion occurred in the lower floors of the building and dozens have been reported injured so far. (AP Photo/Guillermo Gutierrez)

Firefighters belonging to the Tacubaya sector and workers dig for survivors after an explosion at a building adjacent to the executive tower of Mexico's state-owned oil company PEMEX, in Mexico City, Thursday Jan. 31, 2013. A large explosion occurred in the lower floors of the building and dozens have been reported injured so far. (AP Photo/Guillermo Gutierrez)

An emergency worker treats an injured worker of Mexico's state-owned oil company PEMEX after an explosion at an adjacent building to the executive tower of PEMEX in Mexico City, Thursday Jan. 31, 2013. A large explosion occurred in the lower floors of the building and dozens have been reported injured so far. (AP Photo/Guillermo Gutierrez)

A soldier stands guard outside the Pemex headquarters after an explosion in Mexico City, Thursday, Jan. 31, 2013. Mexico's stated-owned oil company says an explosion at its headquarters in the capital has left several workers injured. (AP Photo/Eduardo Verdugo)

A soldier stands guard outside the Pemex headquarters after an explosion in Mexico City, Thursday, Jan. 31, 2013. Mexico's stated-owned oil company says an explosion at its headquarters in the capital has left several workers injured. (AP Photo/Eduardo Verdugo)