Police are not initially giving details about what caused the explosion. Witnesses told Indonesian television that they heard two explosions just as students were starting prayers in a mosque on the school grounds. Many are said to have run out as the building filled with smoke.
"The early information we have indicates that approximately 54 people have been affected," said Police Chief Asep Edi Suheri before a press conference on a television broadcast.
Three are being treated for serious injuries, but no one has died.
Some have minor injuries, some moderate, and some have already been discharged (from hospital).
A suspected crime scene at the school has been cordoned off as technicians investigate the cause of the explosion. The police chief does not want speculation to be made about whether it may have been an attack:
Let the authorities work first. We will let the public know what we find out.
