Police have promised additional patrols in Hendon after the assault of a group of Jewish pupils as they travelled home from school on Monday.
Several JFS pupils were left with minor injuries after four teenage boys climbed on to the school bus while it was stopped at traffic lights, then allegedly punched and struck passengers.
The boys fled when the bus driver intervened. Police said they thought the incident stemmed from a dispute or argument but were looking for witnesses to find out more.
Detective sergeant Becky Bird of Barnet police said: "What we really need is information from the public in order to bring these people to account."
She added: "The police schools' officers are in touch with the school concerned to ensure that police do all they can to reassure pupils."