International aid organisation Save the Children has been able to reunite 69 children with their families in Nepal in the aftermath of flash flooding on Wednesday.At least 682 people have died and close to 3000 are missing after a wall of water and debris swept through the Himalayan region, engulfing entire villages.Five New Zealanders are believed to be missing. They have been named by friends and family as Mihir Patel, Kinnari Patel, Shweta Mhatre, Dejan Kuzmic and Suhasini Reddy.Save the Children's Amy Sawitta Lefevre told RNZ that it was still a search and rescue operation, with her organisation distributing water and food, providing temporary shelter, and administering medical care.Sawitta Lefevre has been in Nuwakot, 50 to 75 kilometres northwest of Kathmandu, since Friday."We have - and the number may have gone up since - but over the past 24 hours, 48 hours or so, we have managed to reunite about 69 children with their families. And that's been wonderful to see."But obviously there's many, many more out there who will need to be reunited with their families as well."People walk through mud alongside collapsed buildings after the flash floods.Dil Kamal Chettri / Save the ChildrenOne of the most urgent concerns for Save the Children was family separation, she said, with children as young as five seeking help.Some children were still wearing the clothes they were wearing when the disaster hit, she told RNZ."We saw lots of kids with grey and muddy clothes, and the children were obviously, you know, they were in need of water, they were in need of food, they were in need of blankets, and they're also in need of medical assistance."Some children had developed upper respiratory tract infections from being exposed to the elements for so long.Overcrowded temporary shelters were another concern. Sawitta Lefevre said the number of children at one holding centre had doubled from 30 to 60 within a couple of hours.The overcrowding risked spreading disease, as well as affecting children's mental health and meaning less protection for them.Save the Children staff pack emergency supplies for flood-affected communities in Nepal.Sarthak Thapa / Save the ChildrenSave the Children expected to remain in Nepal for some time to provide humanitarian assistance."We are looking to stay in Nepal on this response, on this flood response, for a very long time. I mean, we're talking months, if not a year or more here."The humanitarian needs are many and it's not something that we're going to be able to deal with overnight or in a matter of days or weeks. So we're definitely in this for the long haul," Sawitta Lefevre said.