At least two students and a teacher were killed in a rocket attack on a school in central Logar province of Afghanistan early on Sunday, an official said.The education ministry, in a statement here, said the incident took place in Baraki district around 8.00 a.m., Khaama press reported.The Topak preliminary school was targeted in the rocket attack and at least four other people were injured.Local officials, confirming the incident, said the injured were admitted to a hospital nearby.No group, including the Taliban militants, has so far claimed responsibility.Logar is among the relatively volatile provinces in central Afghanistan where anti-government armed militant groups are actively operating in its various districts including Baraki Barak.Sunday's incident comes as the insurgency activities have been on the increase since the Taliban group announced its summer offensive earlier last month and since then staged numerous attacks across the country.