Srinagar, Sep 9 - Four people, three of them securitymen, were injured in a powerful handgrenade explosion in Jammu and Kashmir's Sopore town Wednesday, police said.

A senior police officer said guerrillas tossed a grenade at the heavily guarded Sopore police station building which exploded injuring two Central Reserve Police Force (CRPF) troopers, one local policeman and a civilian. Sopore town is 54 km from Srinagar.

'The injured were taken to a local hospital for treatment,' the officer said.

No group has yet claimed responsibility for the blast.

Earlier, a grenade exploded in the Karan Nagar locality of Srinagar. No damage or casualty was caused.