While one of the injured died in a hospital, the condition of seven others who are now in the emergency department of the Regional Institute of Medical Science and Hospital was reported to be 'serious', sources said.
The spot is about one kilometre south of the official residence of chief minister Okram Ibobi Singh and Manipur police headquarters which is adjacent to Singh's office-cum-residence, sources said.
Immediately after the incident, senior police officials rushed to the spot and blocked the exit points to launch a search but no arrest could be made, sources said, adding that the bomb might have been planted late last night with a timer.
Wednesday's explosion is the second such incident since Monday.
Five persons were injured when a powerful bomb exploded on Monday at Imphal market complex, about one kilometre north of Ibobi Singh's residence and the Raj Bhavan.