The investigation focuses on alleged gun-running operations by some cadres of banned outfits, sourcing weapons from Myanmar and reportedly distributing them across India using forged documents and the help of registered gun houses
The police commandos of all the five valley districts put down their arms asking for action against Metei radical group Arambai Tenggol and no hindrance from political executives when the forces act against the outfit, officials said.
Police had made the first arrest on Thursday, a day after a 26-second video of the horrific incident surfaced on July 19.
Manipur Deputy Chief Minister Yumnam Joykumar's son was booked early April for "spreading false information."
The NIA, which has taken over the case from Manipur police, conducted a thorough search of the area, five days after the attack, the worst on the army in recent times, official sources said. They said the IED was defused by explosives experts from the army.