<p>People watch the AGE refinery fire Wednesday May 5 2010 in San Antonio from a bridge south of the fire An 18 wheeler being loaded with fuel at a San Antonio refinery exploded Wednesday setting off a chain reaction of smaller explosions and sending a towering plume of thick black smoke over the city s southeast side One person was critically burned and the driver of the exploding truck remained missing AP Photo San Antonio Express News John Davenport MAGS OUT TV OUT NO SALES SAN ANTONIO OUT MANDATORY CREDIT< p>