Police officer Capt. Mustofa says the pickup was carrying a group of 29 mourners from East Java's Probolinggo town who were on their way to pay respects to their relative.
He said today the vehicle was moving uncontrollably and collided with a trailer truck. The occupants were thrown from the pickup and 15, including two children, died instantly. The others died in the hospital.
Mustofa, who like many Indonesians uses a single name, said the driver of the pickup was arrested for reckless driving.