In Assam, security has been placed on maximum alert following recovery of grenades and arms and ammunition in huge quantities from different parts of the state. According to intelligence inputs, the banned militant outfits- ULFA and National Democratic Front of Bodoland (NDFB), have taken strategy jointly to strike in some vulnerable spots of the State in the run up to the Independence Day. Security on railways and oil installations besides other sensitive locations has been strengthened. Union Home Secretary G K Pillai on Friday reviewed the internal security of the State in New Delhi with the Chief Secretary Naba Kumar Das and the Director General of Assam Police Shankar Baruah. Meanwhile, a powerful grenade exploded near the Superintendent of Police office at Goalpara last night. However, there was neither casualty nor any damage.