Separatist militants blew up a bus using a landmine that killed at least seven people and injured 25 more in India's restive northeast Sunday, AP quoted police as saying. The incident occurred about 15 kilometers (10 miles) north of Imphal, the capital of Manipur state. Seven passengers died at the scene, said the duty officer at the police control room in Imphal. The officer didn't want to be named because he was not authorized to speak to the media. Four of the 25 passengers injured in the blast were in a serious condition, he said, blaming separatist insurgents for the explosion. No group immediately claimed responsibility for the blast.