NACOGDOCHES (AP) Debris rained down Saturday over hundreds of square miles of Texas and Louisiana, smashing a rooftop, splashing into a reservoir and sending emergency crews on a far-flung hunt for bits of what was once space shuttle Columbia. Across the city of Nacogdoches and the surrounding region of pine forest, residents found chunks of debris. A small tank rested on a runway. A steel rod with silver bolts was roped off behind yellow police tape in a yard. A piece of metal rested in a bank parking lot. Authorities urged the public to report any debris but not touch it for fear of contamination from toxic substances. The Army sent in helicopters and soldiers to locate and guard bits of wreckage, which could be pivotal in determining the cause of the disaster.