Three boys aged 11, 12 and 13 and have been arrested after stones were thrown at a bus in St Helens.
The trio were taken into custody on Monday (April 10) and have been released on police bail.
It follows an incident on Baxters Lane, Sutton, in which two bus passengers were injured.
Police say two windows on the number 35 Arriva bus were broken and a woman aged 47 was taken to hospital for treatment for a head
She has since been released.
A 57-year-old also suffered a cut but did not require hospital treatment.
Chief Inspector Steve Brizell said: “This kind or reckless behaviour can have serious consequences and it is fortunate nobody was more seriously hurt on this occasion.
“We will not tolerate anti-social behaviour in our communities and we currently have extra patrols out tackling this issue.
“At the same time it is important that children and young people understand the potential consequences of such actions.
“We are already doing lots of work with local schools to highlight the dangers of this behaviour, but I would also encourage parents, guardians, teachers and friends of any young people around the area to help us spread this message.
“I would urge anyone in the community who has information about this incident to come forward. At the same time we would like to hear from anybody who has mobile phone footage or any drivers who may have dash cam footage.”
Anyone with information can contact the police via 101 or anonymously through Crimestoppers, on 0800 555 111.