Three children aged 11, 12 and 13 were questioned after a woman suffered a head injury when stones were hurled at a bus in St Helens .
A second bus passenger was also injured as windows were shattered on the number 35 Arriva bus as it travelled along Baxters Lane.
The incident happened on Monday evening and police said they were also investigating reports that stones had been thrown at a taxi.
The three young children were taken to a police station on suspicion of causing criminal damage. They have since been released on bail.
Police said a 47-year-old woman was taken to hospital for treatment and a 57-year-old man also suffered cuts to his head.
The trio were taken to a police station oafter the rocks were launched at the number 35 Arriva bus while it travelled down Baxters Lane.
Chief inspector Steve Brizell said: 鈥淭his kind or reckless behaviour can have serious consequences and it is fortunate nobody was more seriously hurt on this occasion.
鈥淲e will not tolerate anti-social behaviour in our communities and we currently have extra patrols out tackling this issue.
鈥淎t the same time it is important that children and young people understand the potential consequences of such actions.
鈥淲e 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.
鈥淚 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.?/p>
Anyone with information can contact the Police via 101 or Crimestoppers, anonymously, on 0800 555 111.