Three have been seriously hurt and two people have suffered life-threatening injuries in a crash involving two buses in a city centre.

Sussex Police also said there were six to eight "walking wounded" following the collision in the centre of Brighton at 9.22am.

The accident happened in Queens Road, with police declaring it "a major incident".

The crash involved two vehicles belonging to Brighton & Hove Buses and the firm's managing director, Martin Harris, said there would be a "full investigation".

Mr Harris said: "All passengers were evacuated and the emergency services have been in attendance, along with our operational team."

A police spokesman said: "It has been declared a major incident by the ambulance service and police have advised drivers to avoid the city centre for the next few hours."

A walk-in centre and triage centre have been set up for the injured.

The buses involved in a crash in Brighton, East Sussex, which has left two people with life-threatening injuries and three others seriously hurt

Kent, Surrey & Sussex Air Ambulance, South East Coast Ambulance Service and East Sussex Fire & Rescue Service were called to the scene where they were dealing with "multiple casualties", an air ambulance spokesman said.

He added: "A seriously injured patient has been treated by the air ambulance doctor and paramedic and has been taken to the nearby Royal Sussex County Hospital by land ambulance, accompanied by the helicopter team."

Mr Harris said that the driver of one of the buses had received "significant injuries" but could not give further details about his condition.

South East Coast Ambulance Service said a total of 23 patients were treated. Seven were taken to the Royal Sussex County Hospital in Brighton, including the two with very serious injuries.

Six further casualties were admitted to the Princess Royal Hospital in Haywards Heath, West Sussex, and 10 were assessed at the scene but did not need to go to hospital.

At the scene, a road cone could be seen wedged under the front end of the bus which had careered into the other double-decker.

A police officer at the scene after two buses were involved in a crash in Brighton, East Sussex, which has left two people with life-threatening injuries and three others seriously hurt

The driver's windscreen of the rear bus had fallen out, while its upstairs windscreen was shattered.

Members of the public were being held behind cordons at either end of North Street as investigators carried out inquiries.

Paper towels and granules had been laid on parts of the road to soak up any fuel and oil which leaked from the buses.

Inspector James Biggs, of Sussex Police, said it was too early to say whether a medical episode suffered by one of the drivers was to blame for the crash.

Speaking at the scene, he said: "As you can appreciate, on a sunny day in Brighton there were lots of people everywhere.

"It was very chaotic. The main priority was care for the patients. It was declared a major incident very early on.

"We got a very good response from the three emergency services, and we worked very well in the initial stages to make sure the patients got the care and treatment that they needed."

Mr Harris said: "We are exploring all the possible causes and that includes the suggestion that there may have been some sort of medical episode involving the driver."

He said the driver and a passenger, who were taken to hospital with life-threatening injuries, are now said to have "potentially life-changing injuries but that is still serious and a matter of concern".