The accused were taken into custody last night and later arrested, police sources said.
Stones were hurled at the CPI(M) district committee office here last night in which some window panes were damaged.
The glass case in which the bust of late P Krishna Pillai, founder of Communist movement, was kept, was also damaged in the stone throwing.
A BJP procession had passed through the area just before the incident.
State DGP Loknath Behara today said strong action has been taken against those responsible for the violence in the state capital last night.
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Meanwhile, CPI(M) state secretary, Kodiyeri Balakrishnan, visited the CPI(M) office this morning.
"The RSS and BJP's aim is to turn the state capital into a war zone.. Corporation Mayor was attacked by BJP and RSS.. Stringent action should be taken against communal forces and no need to show any leniency towards them," he said.
"Police should take action against RSS and SDPI," he added.
The capital city had witnessed tense moments following the incident.
Meanwhile, BJP has denied that its workers were responsible for hurling stones at the CPI(M) office.
BJP District President, S Suresh, claimed that the incident had taken place only after the BJP procession crossed the area.
"We are also against such violence," he said.
Stones were also hurled at the Bhartiya Mazdoor Sangh (BMS) office yesterday, he alleged.