Police have named two more suspects, identified only as DDS and R, in their investigation of a trek along a river in Sleman, Yogyakarta, that saw 10 students killed in a flash flood.

Police had previously named as a suspect IYA, a physical education teacher at SMP 1 state junior high school in Turi, Sleman, Yogyakarta.

IYA, DDS and R were among seven scoutmasters who chaperoned 249 seventh- and eighth-graders of the school as they took part in a scouting activity, trekking along the banks of the Sembor River, on Feb. 21.

“We have named new suspects; their initials are DDS and R,” Yogyakarta Police spokesperson Sr. Comr. Yulianto said on Tuesday.

The students started trekking on Friday from Dukuh hamlet in Donokerto village, Turi district, Sleman, and walked upstream for about 1 kilometer. During the trek, the river suddenly flooded and strong currents swept away many of the students.

Ten female students were killed, with the joint search and rescue (SAR) team recovering the last two bodies in the early hours of Sunday.

During the excursion, DDS and R were not with the students. DDS was waiting at the finish line and R was at the school.

All suspects were charged under Article 359 of the Criminal Code, which pertains to negligence leading to death, as well as Article 360 on negligence resulting in injuries that carry a maximum punishment of five years of imprisonment.

Yulianto said police had questioned 22 witnesses, including the school’s principal, the manager of Lembah Sempor nature tourism in Dukuh hamlet, the scoutmasters, the students and the students’ parents.

“The suspects — IYA, DDS and R — all have certificates for the Basic-Advanced Course [for scoutmasters]; they are supposed to have knowledge of scouting in nature,” Yulianto said.

However, at the press conference, Yulianto said that only four of seven scoutmasters had accompanied the 249 students on the hike. The students were in the middle of the river trek when the flash flood occurred.

Tita Vhasya Pradita, a 13-year-old girl scout who survived the flash flood, said that, as the students were making their way toward the river, several residents of a hamlet had urged them to stop because of flooding on the northern side of the river.

"I heard the scoutmaster say that it was OK, because our lives were in God’s hands,” Tita said.

Earlier, SMP 1 Turi principal Tutik Nurdiana said she had not been aware of a trekking activity on Friday afternoon.

“Honestly, I didn’t know that [the students] would go on a river trek. The [scoutmasters] didn't tell me,” Tutik said.

Other school officials, however, confirmed the school did hold scout activities every Friday from 1:30 to 4 p.m.

Esti Wijayanti, a member of the House of Representatives Commission X overseeing education and youth affairs who visited the site of the incident, said she would evaluate the school’s scout curriculum, particularly its safety procedures.

“The participants were not even asked whether they could swim,” she said.