Bayu Marhaenjati – Two fuel bombs were hurled into the backyard of St. Fransiskus Assisi Catholic private high school in Tebet, South Jakarta, at around 1:00 a.m. on Tuesday, police said.

One of the bombs exploded, though three school guards and a local man successfully extinguished the resulting fire, Tebet police chief Comr. Nico Andreano Setiawan said.

"The fire was immediately doused with toilet water," he said, adding that the bombs caused no damage or injuries.

Nico said that the guards didn't see who threw the bombs and were alerted only by the sound of an explosion.

"After they checked the site, one of the bombs – which was about the size of a syrup bottle with a burning cloth at one end – was found. Another bottle was broken and on fire," he said.

Nico added that the investigation is still ongoing. "The perpetrator[s] and the motivation remain unknown, and we are still conducting the investigation. It is in the hands of the Tebet detective office," he said.