Indonesian authorities said they have identified a 17-year-old boy as the suspected perpetrator of an attack that shook a mosque at a high school during Friday prayers in Jakarta, Indonesia’s capital, injuring at least 55 people, mostly students.

Police brushed away speculation for now that the blasts were a terror attack, saying they were still investigating.

Witnesses told local television stations that they heard at least two loud blasts around midday, from inside and outside the mosque, just as the sermon had started at the mosque at SMA 72, a state high school within a navy compound in Jakarta’s northern Kelapa Gading neighborhood.

Students and others ran out in panic as grey smoke filled the mosque.

National Police Chief Listyo Sigit confirmed in a news conference at the presidential palace in Jakarta that the suspect was one of two students who were undergoing surgery due to suffering serious injuries in the blasts.

Sigit said police investigators are still collecting all information to determine the motive, including how the suspect was able to assemble a toy submachine gun with words inscribed on it including “14 words. For Agartha,” and “Brenton Tarrant: Welcome to hell."

“14 words” is generally a reference to a white supremacist slogan, while Brenton Tarrant is the perpetrator of a 2019 mass shooting at a mosque and Islamic center in Christchurch, New Zealand, that killed 51 and injured dozens of others.

Most of the victims suffered injuries from glass shards and burns. The cause of the explosions was not immediately known but they came from near the mosque’s loudspeaker, according to Jakarta Police.

Police added the injured were rushed to nearby hospitals and 20 students remained hospitalized for burns, three of them with serious injuries.

Indonesia, the world’s most populous Muslim-majority country, was struck by a major militant attack in 2002 when al-Qaida staged bombings on the resort island of Bali that killed 202 people, mostly foreign tourists.

In subsequent years, there have been mostly smaller, less deadly strikes that have targeted the government, police and anti-terrorism forces, as well as those considered infidels by militant groups.

Friday's attack was not the first mosque attack. In 2011, a Muslim militant blew himself up in a mosque at a police compound in Cirebon packed with officers during Friday prayers, injuring 30 people.

In December 2022, a Muslim militant and convicted bomb-maker who was released from prison the previous year blew himself up at a police station in West Java, killing an officer and wounding 11 people.

Since 2023, the Southeast Asia nation has experienced what authorities call a “zero attack phenomenon,” crediting the government with the stable security situation.

AP video shot by: Andi Jatmiko