An eyewitness recalled seeing emergency services “speeding up and down the road” following a major incident in Southport on Monday, 29 July.
A North West Ambulance Service (NWAS) spokesperson said it had treated eight patients with stab injuries who were taken to Alder Hey Children’s Hospital, Aintree University Hospital and Southport and Formby hospital.
Merseyside Police confirmed that armed officers detained a male, who was taken to a station, and seized a knife.
There is no wider threat to the public, authorities added.
The public has been urged to avoid the area around Hart Street.
Local resident Ian Uzzell told Sky News several air ambulances also arrived on the scene.