The Mayville School bus was travelling along Holbrook Road, Landport, when the attack happened
Terrfified children on the bus were showered with glass.
A dad of a pupil said: ‘Young lads were throwing things and a brick smashed a window.’
The incident happened at about 4.15pm yesterday. The damaged bus had to return to the Southsea school and police were called.
Anyone with information should call Hampshire police on 101.