The Indian Coast Guard has been placed on high alert along the maritime border to prevent any attempt by those behind the Sri Lanka blasts to enter India, central sources said today. The development came hours after the Sri Lanka declared that a local Islamic extremist group -- the National Thowheeth Jama'ath -- may be behind the deadly suicide bomb attacks that killed nearly 300 people on Easter Sunday. There were concerns that those behind the attack may try to escape the island nation by sea.