A gas leak at The Sandbanks Hotel in Poole has been secured by Dorset Fire and Rescue Service.
A harmful chemical was released from plant equipment - with the hotel evacuated and one person taken to hospital.
Fire crews were called to the hotel along Banks Road, Poole at around 10:50 this morning and have now ventilated and made the area safe.
A spokesperson for Dorset Fire and Rescue Service said: "The chemicals concerned - sodium bisulphate solution and sodium hypochloride - when mixed make a chlorine solution which gives off chlorine gas.
"This had escaped from plant equipment into the plant room and surrounding area."
Around 20 firefighters from Poole and Westbourne attended the incident.