Pandey said they were from a group called Hindu Raksha Sena.
"All our volunteers were asked to get inside (the office) when the attack took place," Pandey said, adding the attackers raised slogans against a particular community.
The protestors were agitated over the statement of senior AAP leader Prashant Bhushan who had advocated a plebiscite in Kashmir on deploying army in the state.
