The crash – on a coastal highway east of Jakarta in Situbondo regency on Wednesday night, after which the truck driver fled – killed 54 people including two teachers and a tour guide.
"Yes we captured the driver in Surabaya yesterday. We are now still interrogating him at the (East Java) station," Situbondo Police Chief Tugas Dwi Apriyanto told Reuters.
His comments came as doctors and more than 100 distraught parents and relatives struggled to identify the youngsters, many of whom burned to death when flames engulfed the bus they were in after it and the truck collided.
"The final death toll is 54 victims. Two were schoolboys, 49 were girls. We have succeeded in identifying 12 bodies so far," said Nanang, a doctor at Situbondo Hospital.
He said a forensic team from the East Java police was working to identify the remaining bodies using DNA and dental records.
Police said no charges had yet been laid against the truck driver and he was being questioned as a witness.
"The truck driver and his assistant...are currently being questioned as witnesses," said Apriyanto."
"The investigation is still going on and we will check everything from witness statements and facts we found on the scene."
The injured drivers of the bus and a minivan which ran into the back of the bus after it hit the truck were also being questioned.