At least seven people were killed and 25 injured late on Sunday when a packed passenger bus hit a landmine in northeastern India's restive Manipur state, police said.
"A passenger bus took the full impact of a landmine explosion near Pourabi, 13 km from capital Imphal. Seven passengers have died and 25 are wounded," a police spokesman here said.
This is one of the worst militant attacks on civilians in Manipur, a state of 2.3 million people.
The injured have been brought to hospitals in Imphal.
"We cannot say anything as to which of the rebel groups could be behind today's blast," the police spokesman said.
No militant group has as yet claimed responsibility for the attack.
Manipur has 19 active insurgent groups, almost all of them seeking separate homelands.
No major insurgent group in Manipur has entered into a ceasefire with the government unlike their counterparts in neighbouring Nagaland.
However, the government achieved a success in bringing eight Kuki outfits under a cessation of hostility agreement in October 2005. This agreement has been subsequently renewed.
The army and paramilitary forces in the state have been engaged in a stepped up offensive against the militants.
The latest offensive is against the People's Liberation Army (PLA) in Chandel district. The army has claimed success in this ongoing counter-insurgency drive in the area.