British emergency services said a man had been arrested after at least eight people were stabbed in Southport, northwest England, on Monday, with a local children's hospital declaring a major incident and the prime minister calling it "deeply shocking".

North West Ambulance Service said it had treated eight patients with stab injuries who had been taken to three different hospitals, including Alder Hey Children's Hospital.

Merseyside Police said armed police had arrested a man and seized a knife after being called to reports of a stabbing at around 11.50 am (1050 GMT). There was no wider threat to the public, they added.

"Horrendous and deeply shocking news emerging from Southport. My thoughts are with all those affected," Prime Minister Keir Starmer said on X.

"I would like to thank the police and emergency services for their swift response. I am being kept updated as the situation develops."

Alder Hey Children's Hospital said it had declared a major incident and its emergency department was extremely busy. It asked parents only to bring their children in if it was urgent.