Three schoolgirls sustained cuts after a bus carrying pupils towards Ligoneil in north Belfast had its window smashed by a youth.
Police are treating the incident as a sectarian motivated hate crime.
It happened at around 2.30pm on Tuesday (6 October) when the bus was waiting at lights at the junction of the Crumlin Road and Ligoneil Road.
Inspector Nick Browne said police believe the male youth who threw the object at the bus was in the company of two others and was wearing a grey tracksuit with a black hoodie underneath.
“We are currently progressing a number of enquiries to identify the youths and would ask anyone who witnessed the incident to contact officers at Tennent Street on 101 quoting reference number 993 06/10/20, or submit a report online using our non-emergency reporting form via http://www.psni.police.uk/makeareport/. You can also contact Crimestoppers anonymously on 0800 555 111 or online at http://crimestoppers-uk.org/,” he added.