The boys, from the Skinners' School in Tunbridge Wells, Kent, were travelling on a private bus in a remote mountain area when they were ambushed by a group of bandits who stole around £2,000 in money and valuables.
The 16-year-old boys were two-thirds of the way into a month-long trip organised by World Challenge Expeditions, where they were carrying out volunteer work in local schools.
Head teacher Simon Everson said: "No one was hurt but they will be coming back as soon as flights can be arranged.
"We told the boys we would support them if they wanted to stay or if they wanted to come back and they said they wanted to come back."
Mr Everson said the teenagers were accompanied by two teachers as well as an experienced expedition leader from the organisation.
He added: "It's very rare for this sort of thing to happen I'm told, but all precautions had been taken and everyone, including the boys, had received appropriate training, which they put into practice as soon as it happened."
He said the incident occurred at around 9pm local time on Friday, when the students were on their way to the central city of Coban.