In Imphal, four persons, including two girls were injured in a bomb blast near the Jawaharlal Nehru Institute of Medical Sciences Hospital under Porompat Police Station in East District last evening. Police sources said, the bomb hurled by some miscreants exploded at the main gate of the Hospital. Condition of one of the victims is reported to be serious. Imphal East District SP inspected the blast site and a case has been registered at Porompat police station for further investigation.