Four persons were injured in a bomb explosion at Thoubal Khunou in Manipur, police sources said on Monday.
The IED blast occurred at about 8.30 pm late Sunday near the gate of a mega power sub-station.
It was suspected to have been triggered by unknown people and could be related to monetary demands, a police official said.
The victims were rushed to Thoubal district hospital. Their conditions are said to be stable, the official said.
In an effort to arrest the culprits, combing operations was launched on Monday morning, the police added.
Meanwhile, early on Monday, a blast occurred at Dum Dum Cantonment Railway Line in Kolkata in which one was declared critically injured.
The West Bengal Railway police and security officials were present at the spot. The injured person was taken to a nearby hospital where his condition was said to be critical. The police have recovered 29 more crude bombs from the spot.
The explosion came two days after a live bomb was recovered from an under-construction metro tunnel in Kolkata.
The investigation into the case by the police is underway.