A blast injured dozens of people near a school in Indonesia's capital on Friday, a senior police official said without disclosing the cause of the explosion.
Jakarta police chief Asep Edi Suheri said there was an explosion "in the vicinity" of a high school in the sprawling city.
"The initial data we have received indicates that there are approximately 54 individuals affected," Asep told reporters in comments broadcast by Kompas TV.
"Some have minor injuries, some moderate, and some have already been discharged."
Authorities had cordoned off the area and "were processing the crime scene", Asep said, including a bomb squad from Jakarta police as they tried to determine the cause of the blast.
Asep said authorities had also set up posts in two hospitals to assist relatives in finding injured victims.
"We are still investigating, as this incident just occurred," Asep said.