Six people, including three children, were injured when a car mounted a kerb and ploughed into a crowd of people outside a sports centre in Newcastle.
It happened at about 09:14 BST outside Westgate Sports Centre where an event was taking place to celebrate Eid.
One of the children is said to have been critically injured. Northumbria Police said the incident was not believed to be terrorism-related.
A 42-year-old woman was arrested and is in custody, police said.
No-one else was being sought and extra patrols were in the area to reassure communities, police said.
Hundreds of people were at the event to mark the end of Ramadan.
One eyewitness said: “From what I understand, [a woman who had been at prayer] was about to leave in her car and I believe she lost control.
“I ran up straight away because everyone was moving in on all the injured, trying to put water in their mouths.
“The parents of the kids were there, I had to sort of try and calm them down just to tell them the ambulance is there and they will take care of it; they know what they’re doing.