Three men were stabbed at a popular holiday resort hours after a major incident was declared when thousands of sunseekers flocked to beaches amid the heatwave.
The men, all in their 20s and from London, were hurt during a fight near the amusements on Bournemouth pier on Thursday evening.
The three men were taken to hospital for treatment by the ambulance service.
Dorset Police said one man sustained a stab wound to his back and has since been discharged from hospital.
A second man sustained an injury to his face and the third was injured in the chest and arm.
Their conditions are not described as life-threatening.
Detective Inspector Gavin House, who is leading the investigation, said: “We are carrying out a full and thorough investigation to determine who was responsible for this incident.
“The public can expect to see an increased police presence near to the pier today as detectives continue their inquiries in the area.
“I understand there was a large number of people on the beach at the time of the incident and I would urge anyone who may have important information to assist my investigation to please get in touch.
“I am keen to hear from anyone who may have video footage of the incident and would please ask that you do not post or share this online out of respect for the injured people.”
On Thursday Bournemouth, Christchurch and Poole Council declared a major incident and condemned the “irresponsible” behaviour of crowds who gridlocked roads, dumped rubbish and parked illegally.
Extra police patrols have been brought in and security is in place to protect refuse crews who the council said faced “widespread abuse and intimidation” as they emptied overflowing bins.
Thirty-three tonnes of waste was cleaned up along the full stretch of coastline on Thursday morning, in addition to eight tonnes collected between the piers on Wednesday, the council said.
Council leader Vikki Slade said: “We are absolutely appalled at the scenes witnessed on our beaches, particularly at Bournemouth and Sandbanks.
“The irresponsible behaviour and actions of so many people is just shocking and our services are stretched to the absolute hilt trying to keep everyone safe.
“We have had no choice now but to declare a major incident and initiate an emergency response.”
Bournemouth East MP Tobias Ellwood said 500,000 people had visited Dorset and added his voice to the calls for people not to go to the area.
“This place was deluged and social distancing went out the window and that’s why a major incident was declared, because the local authority and indeed the police couldn’t cope,” he told BBC Breakfast.
“The beach should have been closed down, or at least shut down to prevent further people from entering it.
“We need to learn from this and recognise that if we’re going to be serious about tackling this pandemic then we need to be swifter in being able to provide support to local authorities who are unable to cope.”