Indonesia's president ordered police to hunt down and arrest assailants who stabbed a Christian worshipper in the stomach and beat a minister in the head with a wooden plank as they headed to prayers.
Neither of the injuries appears to be life-threatening.
No-one claimed responsibility for Sunday's attacks.
But suspicion immediately fell on Islamic hard-liners who repeatedly warned members of the Batak Christian Protestant Church against worshipping on a field housing their now-shuttered church.
President Susilo Bambang Yudhoyono, who relies heavily on Islamic parties in parliament, was widely criticised in the media for failing to crack down on hard-liners.
But he immediately called on authorities to investigate and to hold accountable those responsible.