A 16-year-old boy arrested on suspicion of causing death by dangerous driving after a collision on the Shirenewton caravan site, east of Cardiff, has been released on bail pending further enquiries.
A seven-year-old boy was taken to the University Hospital of Wales in Cardiff, where he died from his injuries. Specially-trained police officers are supporting the family.
Police are still investigating the incident, which happened at around 3pm on Saturday. They are appealing for any witnesses to come forward.
More top news
Welcome to the Newsweek Quiz - where we'll be testing your knowledge from the last seven days of news here in Wales.
A 9pm watershed ban on adverts that market junk food to children should be introduced, Wales' Health Minister has said.
It'll be an unsettled afternoon across Wales, with blustery winds and heavy rain. Gales expected in many areas.