Guests at the exclusive Sandbanks Hotel have been evacuated following a "chemical incident".
Fire services were called to the four star hotel on Banks Road in Poole, Dorset, at 10.50am this morning.
A spokesman said paramedics are attending to one casualty at the scene.
Around 20 firefighters from Poole and Westbourne are dealing with the incident, which is believed to involve chlorine gas and liquid.
Hazmat officer and station manager for Dorset Fire and Rescue Louis Minchella said: "A 60-metre cordon has been put in place around the hotel and all guests have been evacuated.
"We are dealing with a gas leak which can be potentially harmful to people.
"Fire crews will be committed in gas-tight suits to investigate and isolate.
"The beach and road surrounding the hotel have been closed."
The hotel - with 108 guest rooms - is situated in one of England's most exclusive locations with direct access to Sandbanks' Blue Flag beach on one side and views of Brownsea Island and the Purbecks on the other.
It boasts seven miles of golden sands with views of Old Harry Rocks, Poole and Bournemouth Bay round to Hengistbury Head and across to the Isle of Wight.
A fire service spokeswoman said: "The chemicals concerned - sodium bisulphate solution and sodium hypochlorite - when mixed make a chlorine solution which gives off chlorine gas.
"This had escaped from plant equipment into the plant room and surrounding area."
She added that fire crews have now ventilated the area and made it safe.