Police were investigating the cause of explosion at the site in Kelapa Gading, North Jakarta

Dozens of people were injured and hospitalised after an explosion occurred during Friday prayers at a mosque inside a school complex in Indonesia's capital Jakarta, police said. 

Police were investigating the cause of explosion at the site in Kelapa Gading, North Jakarta, city police chief Asep Edi Suheri told a televised press conference.

The number of people admitted to hospitals was 54, he said, adding the injuries ranged from minor to serious and included burns.  

News channels KompasTV and MetroTV showed footage of a police line around the school with ambulances standing by. Images of the mosque showed no extensive damage.