Four children are among almost 50 people injured after a car ploughed into a crowd during Liverpool FC's Premier League victory parade on Monday evening, the BBC reported.
Some 27 people were taken to hospital, and two suffered serious injuries - including a child.
A 53-year-old British man has been arrested and is believed to be the driver of the vehicle, BBC reported citing local police.
Police aren't treating the incident as terrorism.
Liverpool mayor Steve Rotheram said he has spoken to both the UK Prime Minister Keir Starmer and Home Secretary Yvette Cooper, who are both getting regular updates about the incident.
"The prime minister says anything we wanted as a city to just let him know,” the mayor said, according to the BBC.
Liverpool's Water Street remained cordoned off late on Monday night, as police continue their investigations.