Hundreds of protesters chanting "kill, kill" set fire to a mosque belonging to a Muslim sect that they claim is heretical, while calls mounted for the group to be formally banned.
No one was injured in Monday's early morning blaze, said national police spokesman Maj. Gen. Abubakar Nataprawira. Several suspects were taken in for questioning.
The attack was the latest targeting the Ahmadiyah sect in Indonesia, the world's most populous Muslim nation. Hard-liners claim the sect, founded at the end of the 19th century in Pakistan, was devised by British colonialists to divide Muslims.
Last week, a team of prosecutors, religious scholars and government officials said the sect "had deviated from Islamic principles" and recommended it be outlawed. There have been several acts of vandalism targeting Ahmadiyah since then.