Police have been called to reports of two "possibly illegal immigrants" hidden under luggage on a coach returning from a school trip to France.
Hampshire police said officers attended Hounsdown School, in Totton, on Saturday afternoon.
A mother, who had been at the school to collect her daughter, told the BBC: "I saw one male with his hood up but I believe there were two males."
Tabi added: "They looked as though they were [aged] between 20 and 30."
The coach had brought the school children home from a two-day trip to Boulogne-sur-Mer.
Tabi said: "My daughter came running over and she said 'Oh my God, there's people sat in where the suitcases are'.
"Obviously it's quite concerning because there were 36 children on the coach and no-one was aware that they were on there.
"I understand these immigrants are wanting a better life but it's not very good targeting a coach full of children."
Hampshire and Isle of Wight Constabulary said: "We were called just before 17:15 GMT on Saturday to reports that two people, who were possibly illegal immigrants, had been found at Hounsdown School in Totton."
The force said no arrests had been made.
The Home Office declined to comment on the incident when contacted by the BBC but said: "The government works closely with law enforcement agencies to tackle illegal migration in all its forms."