Terror groups struck again Sunday in Srinagar, capital of Indian administered Jammu and Kashmir when they lobbed a powerful hand grenade at a paramilitary force bunker in the downtown, injuring four civilians. News agency Indo-Asian News Service (IANS) quoting police officials said the terrorists tossed a hand grenade at a bunker of the Indian Central Reserve Police Force (CRPF) in the city, which missed the target and exploded on the road. "Four civilians were injured in the explosion," a police officer told IANS in Srinagar Sunday.Security officials are jointly searching the area. No group has yet claimed responsibility for the attack. Meanwhile, the bomb disposal squad of the state police defused two hand grenades lying in south Kashmir Pulwama town, 40 km from Srinagar, Sunday morning.