Investigators in the French Alps are examining why a teacher apparently took schoolchildren on to a closed ski run shortly before a deadly avalanche.
Two French students and a Ukrainian tourist were killed in the disaster in Les Deux Alpes area on Wednesday.
Three others - two pupils and the teacher - were injured. Education Minister Najat Vallaud-Belkacem promised an investigation would "throw all light" on the circumstances of the tragedy. The two who died were a boy of 14 and a 16-year-old girl from Saint-Exupery high school in Lyon.
Visiting the school, the minister expressed her condolences to the victims' families and urged their peers to "stay strong".
Risk signposted
A huge rescue operation was launched after the avalanche struck the group of 10 teenagers, their teacher and the Ukrainian, 57, on the Bellecombe piste at about 15:45 local time (14:45 GMT).
The piste, which has the most difficult black rating, had been closed since the beginning of the ski season because of a lack of snow, a manager at Les Deux Alpes told local media.
However, large quantities of snow have fallen on the French Alps in recent days, raising the risk of avalanches, the regional government said (in French).
As attention focused on the role of the teacher, officials said the danger had been well signposted, with netting blocking the top of the run.
"How could you consider taking children, after a period of heavy snow, on to a piste that was closed?" Patrick Kanner, Minister for Sport and Youth, told Europe 1.
"The reason why the teacher, who is himself wounded, took them on to the closed run... is something the judicial inquiry will establish," said Mr Kanner.
As well as the three who died, two other pupils were found injured and the teacher was unconscious after suffering multiple broken bones.
The teacher remains seriously ill in hospital but all other members of the party are now "safe and sound", according to the French interior ministry (in French).
'Sincere condolences'
Witnesses told France Bleu radio that the avalanche was likely to have been triggered by groups skiing through the area.
The run is situated on a particularly icy north-facing side of mountain, the radio station said.
Students and their families lit candles and laid tributes as remaining members of the ski party returned to the school in Lyon on Wednesday evening.
The education minister told reporters: "A investigation has been launched. All light will be thrown on the circumstances of this tragedy."
French President Francois Hollande offered "sincere condolences" to the victims' families and said "the solidarity of the whole nation" was with them.
Four other people - two Lithuanians, a Spaniard and a Czech - have died since the New Year in avalanches in the French Alps, AFP reports.
The regional government has urged skiers and other mountain users to take extra care and stay on marked pistes.
