The local officials confirmed the incident took place in the vicinity of Domand district in northern part of the province.
Provincial governor’s spokesman Mubariz Mohammad Zadran said the government has received reports regarding the six students who suffered injuries in the attack.
He said the health condition of a number of the wounded is critical but there are still no reports regarding the Afghan forces casualties.
In the meantime, another official said at least three Afghan security personnel were killed in the attack and some others were wounded.
The eyewitnesses and local residents said the explosion was powerful enough to shatter the glasses of the several houses in the area.
No group has so far claimed responsibility behind the incident.
Khost is among the relatively peaceful provinces in southeastern parts of the country but the anti-government armed militant groups have recently increased their insurgency activities in this province.
Some terrorist related activities and explosions were also reported in the provincial capital and other parts of the province last month.