Emergency services were called to the New York Hotel at Disneyland Paris on Friday after 22 people were accidentally poisoned by a mix-up in pool chemicals. According to local sources, three hotel employees and one guest were transported to the hospital with non life-threatening injuries.

Staff called for a full evacuation of the hotel swimming pool as well as its surrounding rooms after the pool emitted a harmful chlorine gas — the result of incorrectly mixing bleach and sulfuric acid.

Upon arrival, firefighters continued to evacuate the area and treat those affected, who mostly complained of breathing problems and nausea. Only after firefighters drained the pool around 5:30 p.m. local time were guests invited to return to their hotel rooms, though the staff offered to relocate them to a different hotel wing.

The pool remained closed until Saturday morning when guests were given the all clear to use it again.

Abigail Carpenter is Editorial Assistant of AQUA Magazine.