Hundreds of Nepali schoolchildren were saved by quick-thinking teachers during last week's catastrophic floods, with one head teacher evacuating about 1,600 students moments before the school was inundated.

Rajendra Dawadi, head teacher at Tribhuvan Trishuli Secondary School in Nuwakot, received calls warning of the incoming disaster. Speaking to the BBC, Dawadi said: "If we didn't make a quick decision, if it was 10 minutes later, we all, including the students and me, wouldn't be able to speak to you today." A parent arrived saying a big flood was coming and wanted to collect their child. "Parents don't rush without a strong reason, so it was confirmed that I shouldn't waste a second to evacuate the children," Dawadi said. "I decided I shouldn't delay any more. Even if the flood was not coming, it was just a matter of a single day's classes."

Local resident Surinder described how the flood "swept away the entire building" at the school. "Here used to be a three-storey school building in front of a temple and there was a market nearby," he told ABC News. "When floods hit this area, the teacher evacuated all the students and saved their lives."

At another school in one of the worst-hit areas — Shree Bagheswori Madhyamik School in Galchhi — children survived when they happened to leave their classroom for their lunchbreak. Teachers at that school also told students to quickly evacuate classrooms before floodwaters crashed in.

Lakshmi Shrestha, mother of a student, said teachers instructed children to leave their bags and lunch boxes behind. "That's how they managed to survive," she said. The majority of children from that school appeared to have survived, families said. On Sunday, mothers returned to find their children's belongings and see what could be salvaged.

Thick brown and grey mud now coats the surfaces of school benches, walls, and notebooks.