An explosion rocked an Indonesian naval armoury onWednesday, injuring 25 people, dpa quoted the military as saying.It was not clear what triggered the blast at the armoury attached toa naval base in northern Jakarta,armed forces spokesman IskandarSitompul said."We are investigating whether it was caused by an electrical shortcircuit or another thing," Sitompul said.Most of the injured were navy officers, he said.