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)