Akhir 19, 1432 H/March 24, 2011, SPA -- A 9-year-old Polish girl died Thursday after an explosion of what was likely a bomb left over from World War II in a field in southern Poland, according to dpa. The girl was the second victim of the explosion, which occurred Tuesday in the village of Konskowola. The explosion also killed the girl's 10-year-old brother on the spot. The pair were playing in a field when they found the device. Police are waiting for test results to determine what caused the explosion. Unexploded bombs from the World War II-era are frequently found in Poland. Casualties are rare. In February 2010, engineers removed a wartime bomb from the construction site of the National Stadium in Warsaw, which is being built for the Euro 2012 football championships.