Students mourn in front of the Joseph-Koenig Gymnasium. (AAP)  The German students killed in the French Alps plane disaster had won the trip in a lottery of their classmates, according to local media.  The 16 students and their two female teachers had been on a week-long exchange trip near Barcelona, paying a reciprocal visit after Spanish youngsters came in December to the northwestern town of Haltern, reported local daily the Halterner Zeitung in its online edition.  A sea of lit candles and flowers has covered the front steps of the Joseph Koenig Gymnasium where bereaved pupils wept and hugged to share the pain of losing their friends in Tuesday's tragedy.  "Yesterday we were many, today we are alone," read a hand-painted sign at the school, decorated with 16 crosses - one for each of the victims, most of whom were around 15 years old.  The teenagers, 14 girls and two boys, were among at least 72 Germans who made up nearly half the disaster's total death toll of 150.  "Life dreams were shattered from one minute to the next," an ashen-faced headmaster Ulrich Wessel said during a televised press conference.  Education Minister of the German state North Rhine-Westphalia Sylvia Loehrmann, center, arrives with flowers. (AAP)  He said the students' deaths left "a wound that will heal very slowly and leave deep scars".  Across Germany flags are to fly at half-mast for three days to mourn the victims.  Condolence books were opened in Haltern's town hall, Berlin's Protestant Cathedral and at Duesseldorf airport, where the doomed jet had been due to land.  At the school, red-eyed parents and students wept and comforted one another on a day of mourning, as all classes were cancelled and 50 counsellors were on hand to lend emotional support.  Students stand in front of candles placed on the steps. (AAP)  The town of about 38,000 people is small enough for many people to be touched directly by the tragedy, said locals.  Town mayor Bodo Klimpel said that "right now it's very, very difficult to imagine when things will return to normal.  "My son goes to the same school, he's one grade below those who died in yesterday's accident and of course he knows them all," he told news channel NTV.  The dead included six crew and 144 passengers.  Do you have any news photos or videos?
Bereaved German pupils have wept and hugged near a memorial for their 16 fellow students who died in a plane crash in the French Alps.