A team of Bangalore Police carried out the operation and they were assisted by its Tamil Nadu counterpart.
Sixteen people were injured after an explosive placed on a parked motorcycle went off near the BJP headquarters on the morning of April 17.
The incident triggered apprehension about political leaders being targetted just ahead of the May 5 assembly elections. April 17 was also the last day for filing nominations for the elections and top BJP leaders of the state were due to arrive at the party office during the day.
The Union home ministry had confirmed it to be an act of terror and the Union Home Minister Sushilkumar Shinde ordered an inquiry.