The motive for the attack was not unclear but police stations have been frequent targets for radicals in the world's biggest Muslim majority nation, which has long struggled with Islamist militancy.
Naik had been charged with making inflammatory speeches and questioned by local police over his intent to provoke a breach in peace by making remarks about Hindu and Chinese communities living in the Muslim-majority nation.
Widodo held off declaring victory after the unofficial results last month as Subianto insisted he was the archipelago's next leader.
