(WASHINGTON)—A U.S. gunship attack on a hospital in Afghanistan that killed 42 people occurred because of human errors, process errors and equipment failures and none of the crew knew they were striking a trauma center, a top U.S. general said Friday. No criminal charges have been leveled against U.S. military personnel for mistakes that resulted in last’s year’s attack on the civilian hospital in Afghanistan operated by the medical charity Doctors Without Borders.