At the time of going to press, one youngster - 17-year-old Natasha Jade Paton, from Cleghorn, South Lanarkshire - had died and several others were seriously injured after the bus plunged off a bridge in atrocious weather.
Other pupils were described as "walking wounded", according to the police.
Two casualties were airlifted by helicopter to Glasgow's Southern General Hospital, with others taken to local hospitals for treatment.
The bus, carrying 39 children and five teachers, was going to Alton Towers but crashed shortly after setting out, around 6am.
It came off the road and into a burn in heavy snow on the A73 at Wiston, near Biggar in South Lanarkshire.
Past and present Lanark Grammar pupils posted messages on social networking site Facebook, sending their best wishes to those involved and their families.
One commented that the bus should never have left Lanark. Others agreed, adding: "driving was mental enough last night! of course it was gonna be worse in the borders!"
Another said: "i agree bus should not have left! hope all ok xx"
According to the youngsters, one pupil had suffered a broken nose and another a broken shoulder. One was said to have been knocked unconscious and a boy was suffering from hypothermia.
South Lanarkshire Council education director Larry Forde said his thoughts and prayers were with the family of the senior student who died, and all who were injured.
He continued: "The school organised its annual trip to Alton Towers as a welcome break for sixth-year students from their exam preparation before the Easter holidays.
"The headteacher Mark Sherry and everyone connected with the school wish to express their sympathies to all those involved."