The Khost media office said people originally from Pakistan's Waziristan region, which is just over the border and where for years various militant groups have operated, were among the casualties.
Pakistan's foreign office did not immediately respond to a request for comment.
Afghanistan's Taliban-run administration has faced an insurgency by Islamic State militants, who have claimed a series of deadly attacks targeting civilians, foreigners and Taliban security forces in recent months
Pakistan, meanwhile, has seen an increase in violence by Pakistani Taliban militants fighting the state, and it has complained that Afghanistan's Taliban are not doing enough to suppress the militants based on their soil.