Dozens of distraught parents have flown to Switzerland from Belgium after a deadly bus crash left 28 dead, including 22 children.
The vehicle, carrying mostly12-year-olds, crashed into the wall of a tunnel in Sierre as it was heading back to Belgium following a ski trip, police said.
Some of the parents, gathering at primary schools in Belgium before boarding a military aircraft, did not know whether their children were dead or alive before they set off.
Family members, who flew to Geneva from Belgium, were escorted to the Valais canton when they landed. Some began visiting injured children in the Sion hospital, while others were being counseled by psychologists in crisis groups.
The Belgian Prime Minister Elio Di Rupo said: "When one loses an adult it is dramatic but when one loses a child no words can be expressed because the pain is so intense and personal.
"For a child suffering in a hospital or disappearing, no words can be expressed, and in what we still have to deal with, and there is a lot to do, the most important thing is to relieve the families and to strengthen the collaboration between Switzerland and Belgium which is truly remarkable."
Police said the bus, carrying students from two different schools, veered and hit a kerb, then rammed into a concrete wall in the tunnel.
The front of the bus was heavily damaged and blocked people from getting out. The cause of the crash has not been determined.
Twenty-four children remain in hospital, including three children who are in comas, Jean-Pierre Deslarzes, a doctor heading the rescue operation, said.
He added: ""Three children are potentially gravely injured and we hope that their condition stabilises, but we must remain guarded,"
Around 200 police, firefighters, doctors and medics worked through the night at the scene, while 12 ambulances and eight helicopters took the injured to hospitals in the region.
Our Europe Editor James Mates said: "What the Swiss authorities are able to tell us is what they think didn't cause the crash. They have very little idea of actually what did.
"We know that the weather was good, that the road was dry, they are pretty sure that the coach was not speeding, the driver was well rested, this at the very beginning of what was going to be a long drive back to Belgium.
"They might find clues in the wreckage as to exactly what did but it's perfectly possible that they may simply never know."