The A1 southbound was closed at Stamford for several hours on Friday afternoon (28 February) after a van collided with a school bus carrying pupils from Casterton Business and Enterprise College.
The van driver had to be cut free from his vehicle after the crash, which happened at about 2.30pm between the A606 Empingham Road and the A6121 Tinwell Road.
An air ambulance landed on the northbound carriageway before taking the driver to Queen’s Medical Centre in Nottingham.
Two Year 16 pupils who were travelling on the schoolbus were taken to Peterborough City Hospital as a precaution.
Principal of Casterton Business and Enterprise College Victoria Crosher said the school bus was carrying 35 pupils from the school to Ketton when the accident happened.
She said school staff immediately travelled to the scene to be with pupils, who were all aged between 11 and 16.
Mrs Crosher said: “Obviously school staff attended as soon as we heard about the accident and we were able to support the youngsters. All the students behaved impeccably and were very calm.
“The bus was operated by Mark Bland and they very promptly sent another bus so the students could continue home.”
The northbound carriageway reopened earlier and the southbound has now re-opened but police have said there are still delays as traffic is moving slowly near the scene .