The improvised explosive device was planted near the residence of K Leisio and was detonated with a remote control at around 5 pm, police said.
The injured persons have been rushed to the Shija hospital for treatment, they said.
A case has been registered at Lamphel police station.
Leisio is the the Naga People's Front (NPF) candidate of the Phungyar (ST) assembly constituency in Ukhrul district where elections will be held on March 8.
The campaign for the first of the two-phase Manipur Assembly election, scheduled for next Saturday, ended this evening.