A 17-year-old boy has been injured during disorder at a shopping centre which included reports of a group armed with a machete.
Officers were called to Merry Hill in Brierley Hill, Dudley, at about 15:30 GMT on Friday following an altercation involving two groups.
It was believed one was chased through the complex by the other, police said, with the boy sustaining a small cut to his back from a weapon thought to be a machete, which needed medical attention.
The West Midlands force said it was working to understand who was involved, adding that officers had been in the area to provide reassurance.