Separatists planted a land mine that killed at least seven people and injured 25 more in India's restive northeast Sunday, police said. The incident occurred about 15 kilometers north of Imphal, the capital of Manipur state, where more than a dozen insurgent groups are fighting for the frontier's state's separation from India. 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.