Semarang. A pre-dawn explosion inside a home in Semarang, Central Java, killed a 9-year-old boy on Friday and prompted an ongoing police investigation into its cause.

The victim was found dead in a bedroom identified as the source of the blast. Forensic officers discovered a crater on the floor, indicating the force of the explosion, though the exact cause remains unclear.

“We found a crater measuring about 30 centimeters in diameter inside the room,” forensic officer Totok Tri Kusuma told reporters at the scene.

Preliminary findings did not uncover firecrackers or materials typically associated with homemade fireworks, which are a common cause of domestic explosions.

“We recovered residue from the explosion, but the type of material used is still under analysis,” Totok said.

Although several fireworks were found at the location, investigators determined they were not directly linked to the blast.

“The fireworks found at the scene were not part of the material that exploded,” he added.

Initial analysis suggests the explosion may have been caused by a low-grade explosive substance weighing between 1 and 2 kilograms. Authorities said such chemical mixtures can become highly sensitive and may detonate due to friction or heat.

Police are continuing their investigation to determine the exact composition of the materials involved and to reconstruct the sequence of events. Authorities have also urged the public not to attempt to assemble explosive materials, warning of the serious safety risks involved.