Tour operator Chameleon said the small party landed at Heathrow Airport on a South African Airways flight from Johannesburg.
The college said the six were "understandably distressed following the tragic bus crash" and the others would follow when they were fit to travel.
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Hide AdThe party, from Brooksby Melton College in Leicestershire, were on a field trip as part of a foundation degree in animal management and welfare when the accident happened.
Eleanor Payne and Samantha Lake, both 19, were killed when their driver apparently lost control on a bend on Thursday morning. Fellow student Daniel Greenwood, 22, died later in hospital.
The trio were among a group of 18 students and two teachers on the trip.