Officers investigating an explosion at a Santa Cruz high school found more than 40 homemade bombs at a student’s house, police said. Sgt. Bill Aluffi said police were called to Harbor High when a small bomb blew a hole in the bumper of the youth’s car in the school parking lot. The 16-year-old admitted he was making bombs. The devices were fashioned from small compressed-air cartridges of the type used in air-powered weapons. Aluffi said the bombs could blow off a hand or arm and could be fatal if they exploded near someone’s head. Police were investigating reports that the youth had been selling the bombs to students.