Four children were among dozens injured after a car was driven into a crowd of pedestrians who had watched Liverpool FC's open-top bus Premier League trophy parade.
The people carrier struck a dense crowd on Water Street in the city centre at shortly before 18:00 BST - an attack not being treated as a terrorist incident by police.
Merseyside Police said a 53-year-old white British man from the Liverpool area, believed to have been the driver, was detained at the scene and added it is not looking for anyone else.
One child and three adults had to be freed from under the vehicle by fire crews, and of 27 people taken to hospital, one child and one adult suffered "serious injuries".