Terming yesterday's incident as "very unfortunate", Vijayan wanted everybody to see the case as an isolated one and ensure that it would not cause hurdle in the peace efforts in the district.
"Concerned persons have to be cautious to see that the situation is not turning worse. The government will make all efforts to bring the guilty before law," he told reporters here.
Meanwhile, the BJP demanded that Kannur be declared as a "disturbed area" and impose Armed Forces (Special Powers) Acts (AFSPA) citing "frequent" attacks on its party workers.
Later talking to reporters, Rajagopal said the party wanted to declare Kannur as a disturbed area and impose AFPSA as the state police had "failed" to maintain law and order.
More From This Section
"The only solution to maintain law and order is to hand over the law enforcement of the district to the army," he said.
He also alleged that the local CPI(M) leaders have "taken over the control of police" in the district.
Biju was an accused in a case relating to the killing of CPI(M) activist C V Dhanraj in 2016.
Police today registered a case against seven identifiable persons in connection with the incident.
Meanwhile, the dawn-to-dusk hartal, called by the BJP in Kannur and nearby Mahe to protest the killing was total with shops and business establishments remaining closed.
The hartal was peaceful so far except some sporadic incidents of stone pelting, police said, adding that security was intensified and additional force deployed across the district to avoid any untoward incident.