Mandailing Natal Disaster Management Agency head Yasir Nasution said the flood suddenly arrived at 4 p.m. while the students were in class at SD No. 235 state elementary school.
“Eleven students were found dead, while dozens are still missing,” Yasir told The Jakarta Post on Saturday.
He said search and rescue teams were on site trying to find the missing students, but were hampered by disrupted telecommunications and access in the area.
It was also reported on Saturday morning that another two, a police officer and a bank official, died after a vehicle that carried them fell into the overflowing Aek Saladi River.
The heavy rain earlier caused floods on Thursday that inundated Sikara Kara village, cutting road and electricity access in the area. A bridge also collapsed because of flooding, but there were no casualties in the incident.
Another flash flood hit Sibolga, the city in the north of the province, on Thursday, killing a family of four. Their bodies were found under the rubble of their house in Sibolga Ilir subdistrict.
Sibolga mayor Syarfi Hutauruk sent his deepest condolences for the deaths of the four residents. He explained that rainstorms had occurred in several areas in Sibolga since Thursday at noon, prior to the flooding
Several areas in Sibolga, Syarfi went on to say, are prone to flooding and erosion when the rainy season comes, especially in Ketapang and Dolok Martimbang.
“Some areas here [in Sibolga] are prone to disaster, that’s why we always ask the public to be cautious, especially for those who live on the riverbanks or hill slopes,” Syarfi said on Friday.
In Simalungun, a severe flood killed a husband and wife who were dragged by the strong currents that struck their house. Their bodies were found 2 kilometers away from their house.