Jakarta. Multiple explosions shook the mosque of State Senior High School 72 (SMA Negeri 72) in North Jakarta during Friday prayers, injuring at least 15 students and five teachers, police said.

The blasts occurred around 12:30 p.m. at the school, which is located within a Navy compound in Kelapa Gading, North Jakarta. Authorities have yet to determine the cause of the incident.

According to witnesses, the explosion came from the rear section of the mosque’s main hall, sending worshippers scrambling for safety.

“The sermon had just started when we heard a loud blast,” said Budi Laksono, a mathematics teacher who was inside the mosque. “Smoke quickly filled the room. The students ran out -- some were crying, others fell in panic.”

Most victims suffered minor injuries from glass shards and sound shockwaves. The wounded were taken to the Kelapa Gading district clinic for initial treatment.

Shortly after the incident, Navy personnel and Jakarta Police officers cordoned off the area while the bomb squad conducted a full sweep of the site.

Initial inspections have not yet confirmed the cause of the explosion. Investigators are considering several possibilities, including an electrical short circuit or electronic device malfunction. However, they also discovered suspicious objects near the scene -- including components resembling a homemade explosive device, a remote control, and airsoft and revolver-type firearms.

Police said the investigation is ongoing and that all evidence will be examined by forensic and bomb-disposal experts.