Four blasts, three in capital Imphal and one in Thoubal town, took place during Independence Day celebrations on Wednesday.
Four persons, including three women sustained injuries, when an improvised explosive device was detonated around 7:30am at the Thoubal parade ground.
The other three bombs exploded in the capital complex here while chief minister O. Ibobi Singh was giving his speech at the 1st Manipur Rifles parade ground where the I-Day celebrations was taking place.
The ground is situated about two km away from the site of the explosions.
Police and para-military forces rounded up several persons, but freed them after verifying their credentials, reports said.