Police say at least 18 people have been injured by a grenade blast at a bus station in the Indian-controlled portion of Kashmir. They say the grenade was hurled at the main bus station in Jammu city on Thursday and rolled beneath a bus, where it exploded. The injured were taken to a hospital, including at least four who were in critical condition. Police say they are investigating who was responsible. In the past, Indian authorities have blamed rebels fighting against Indian rule in the disputed region for similar grenade attacks, often without producing any evidence. Rebels have in turn accused government agents of carrying out the attacks to defame their movement. India and Pakistan each claim the divided territory of Kashmir in its entirety.