A 12-seater taxi crashed into the bollard barriers.
Richard Coleman, spokesperson for the City's Traffic Services, said no other vehicles were involved in the crash, which happened at 7am, and the reason for the incident remains unknown.
He said the driver of the 12-seater minibus taxi and 11 pupils - three girls and eight boys - were seriously injured.
Another 11 pupils - seven boys and four girls - were slightly injured.
All of those injured were taken to the hospital and there were no fatalities.