Indonesian authorities say a 17-year-old suspected of carrying out last week’s bombing at a high school mosque in Jakarta assembled small explosive devices at home by following online instructions.

The teenager, who has not been named, was among 96 students injured in the blasts on Friday and remains hospitalised following two surgeries.

Police said he acted alone and had no links to militant networks. Investigators said he built seven devices, four of which detonated, using basic materials such as 6-volt batteries, plastic containers, remote controls and nails. The remaining unexploded devices have been secured.

Officials also recovered a toy submachine gun belonging to the teen, inscribed with names and symbols associated with extremist figures, including convicted international neo-Nazis, the Christchurch mosque attacker, and the Columbine High School shooters.

Because of his age and the circumstances, the suspect cannot be charged under Indonesia’s anti-terrorism laws but may face premeditated serious assault charges, which carry a maximum prison sentence of 12 years.

Authorities report that more than half of the 96 injured students suffered hearing loss, including four with sudden deafness. Eleven students remain under treatment, including one in critical condition from burns.

Police continue to investigate the incident and monitor potential safety risks at schools and public spaces.

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