Alton Towers was evacuated after reports of an "unusual smell".
Emergency crews descended on the theme park after the alarm was raised at 12.45am. Investigations have been carried out by Staffordshire Fire and Rescue Service and West Midlands Ambulance Service.
The smell was reported in an employee-only kitchen within the conference centre, reported StokeOnTrent Live.
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A fire service spokesman said: "We were called to the Alton Towers Resort following reports of a suspected chemical-related incident within an employee-only kitchen area. Crews from Cheadle, Ipstones and Longton attended and carried out an assessment, with specialist equipment, which recorded no readings of any concern.
"Two people were assessed by West Midlands Ambulance Service and discharged at the scene. Guests were temporarily evacuated as a precautionary measure. Crews later confirmed it was safe for the public to re-enter and advice was given to staff."
West Midlands Ambulance Service sent an ambulance, two paramedic officers, and its hazardous area response team to the theme park. An ambulance service spokesman said: “We were called to reports of a possible chemical incident within an employee-only kitchen area. Two patients were assessed by ambulance staff and received self-care advice before being discharged at the scene.”
The Alton Towers guests continued to be fed and watered during the evacuation.
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