More than 50 people have been injured in explosions during Friday prayers at a mosque in Indonesia, with authorities identifying a 17-year-old student as the suspected perpetrator.

The incident happened at around 12:15 local time (05:15 GMT) inside a school complex that housed the mosque in Kelapa Gading – a district in the capital, Jakarta.

The victims, mostly pupils, sustained a range of injuries, including severe burns. The suspect was also hurt, according to Indonesia’s police chief, Listyo Sigit Prabowo.

He added that an investigation into the incident is under way, “including how the suspect assembled and carried out the attack”.

A bomb disposal team was deployed to the state-run high school complex following the explosions to collect evidence and ensure there were no other explosive devices.

A pupil at the school alleged to Indonesia’s government-owned news agency Antara that a homemade bomb had been brought In by a student who had often been bullied by other students.

Other pupils told Indonesian news outlets that the suspect was a “loner” who often made drawings depicting violence, and who had been found lying on the ground following the explosion.

A cook at the school described seeing white smoke coming from the mosque and broken windows after the “massive” blast.

“Our hearts were beating fast, we couldn’t breathe,” she told the Reuters news agency.

A high-ranking Jakarta Metropolitan Police officer confirmed the presence of two objects resembling firearms at the scene.

Images from Antara suggest one of the objects appeared to be a submachine gun and another looked like a pistol.

The submachine gun-type object appears to be inscribed on its barrel with: “14 words. For Agartha.”

On its body, it says: “Brenton Tarrant. Welcome to Hell.”

Brenton Tarrant is the perpetrator of a 2019 mass shooting at a mosque and Islamic centre in Christchurch, New Zealand, that killed 51 and injured dozens of others.

A minister who visited the scene later on Friday sought to dispel suggestions that weapons were present at the site, telling CNN Indonesia what had been pictured “turned out to be a toy gun, not a real gun”.

Lodewijk Freidrich Paulus also called on the public not to presume the explosion was a “terrorist act” as investigators were still combing over the scene.

Another object found at the site was a dark green belt for storing gun cartridges.

Indonesia has the world’s largest Muslim population. (BBC)