One child being treated at a hospital in the Swiss capital Bern will be flown home by the end of the weekend, spokeswoman Florence Renggli told reporters in Valais' main city of Sion.
A further three children are being treated at a specialist unit in nearby Lausanne.
"The priority for the hospital is to stabilize their vital functions," said Renggli.
The hospital in Lausanne said the three girls were put into an artificially induced coma because of multiple fractures and other serious injuries. Two of the girls with head injuries remained in a coma due to neurological problems, the hospital said in a statement, while the third with a spinal injury regained consciousness and was able to speak to others around her Friday.
"Our thoughts are for the friends of our daughters," the girls' unnamed parents were quoted as saying in the statement, referring to the other children who were on the bus. "We think a lot of them and their parents."
All EU flags hung at half staff along the EU Commission headquarters to mark the occasion.
At the KBC bank, automatic teller machines read: "We are speechless. All of KBC shares in the sorrow in silence."
Broadcasters rescheduled their programming, with VTM postponing the live finale of its popular singing contest "The Voice of Flanders" for a day.
Special ceremonies were held at the two schools that shared the bus bringing pupils home from Switzerland. In Heverlee, the school gates were plastered with children's drawings about the tragedy. Primary school children stood in silence before releasing white balloons up in the sky.
On Thursday evening, hundreds packed the Holy Cross Church in Sierre, the city in southern Switzerland where the crash took place, for a memorial Mass.
John Heilprin and Frank Jordans in Geneva, Jeffrey Schaeffer in Sion, Switzerland and Mike Corder in The Hague, Netherlands, contributed to this story.
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