A driver and five students were injured Tuesday morning when a school bus hit a mail box and ran into a ditch in Bucks County. It happened at Mechanicsville and Street Roads, on the border between Buckingham and Solebury Townships.  The driver, 26-year-old Jason Arinsberg of Richlandtown, was operating a First Student Company bus on a Central Bucks School District run, taking students to Our Lady of Mount Carmel Catholic School in Doylestown.  None of the injuries were serious.