Priest Albert Pandiangan, 60, was holding the holy ceremony at the altar when the 18-year-old fanatic rushed towards him with a backpack bomb and tried to blow himself up.
Priest Albert Pandiangan
But the bomb burned without setting off the explosives, so the terrorist pulled an axe from his bag and slashed the priest's arm at St Yoseph Church in Medan, the capital of North Sumatra in Indonesia.
The congregation then stepped in and managed to wrestle the axe from his grasp, detaining him until the police arrived.
As officers marched the suspect to the car, pictures show his white trousers soaked in blood. Police found his ID card and a hand-drawn picture of the ISIS flag.
The young fanatic also told police that he was not working alone.
He was later pictured at the police station with an officer holding his bloody head off the ground, where he was lying handcuffed.
The priest suffered slight injuries and has been taken to hospital near where it happened.
Police are still investigating the man's motive, Daily Mail reported.
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