Gunmen on motorcycles force the convoy to stop and then open fire . At least one driver is killed , police say . Pakistan closed its supply routes into Afghanistan after an explosion killed Pakistanis . Islamabad , Pakistan ( CNN ) -- The incident sparked a diplomatic crisis between Pakistan and the United States .
Gunmen on motorcycles force the convoy to stop and then open fire . At least one driver is killed , police say . Pakistan closed its supply routes into Afghanistan after an explosion killed Pakistanis . The incident sparked a diplomatic crisis between Pakistan and the United States .