Four bomb blasts have rocked the Manipur valley this morning. The first blast took place at 7:35 this morning near Thoubal Melaground under Thoubal Police Station in Thoubal District. Two persons have been injured in the incident. The second blast took place at Sagolband Salam Leikai under Lamphel Police Station in Imphal West at 8:30 in the morning. The third and fourth blasts took place at Telipati at 9:40 and at Mahabali area in Yaiskul at 10:40 in the morning under Porompat Police Station in Imphal East District. There is no report of any casualty in the last three blasts so far.AIR correspondent reports, after four powerful bomb blasts have rocked Manipur valley this morning, Police patrolling and frisking at the critical points of the main routes of Imphal city and Thoubal have already been intensified. Police had immediately rushed to all the four blast sites and conducted search operations. However, no one has been arrested so far in connection with the blasts. It may be mentioned that Manipur Police took up unprecedented security measures in the four valley districts of Imphal West, Imphal East, Thoubal and Bishnupur to prevent any untoward incident in view of the Independence Day celebration total boycott called by insurgent outfits of the state.