"It`s true the vessel exploded on its engine," Chief of the National Police Public Relations Division Inspector General Setyo Wasisto said in a short message text on Sunday.
The vessel owned by the transportation office of the Seribu Islands district exploded when it was about to return to Pramuka island.
All the victims have been rushed to a regional general hospital in Pramuka Island for treatment, he said.
Police are still investigating the cause of the explosion.
Reported by Anita Permata Dewi