Some 40 people had to be treated for breathing problems after a chemical leak at a Havel holiday park in Norfolk.
According to Norfolk Fire Service, vehicles including an environmental protection unit had to deal with a chlorine leak, which affected a swimming pool at the park.
Emergency services were first called to Wild Duck Holiday Park near Great Yarmouth at 2:30pm, and the pool was declared safe at 5:30pm.
Chlorine has been used as a chemical weapon, and the leak meant all 40 swimmers had to be taken to hospital, suffering breathing and asthma problems. They are all described as being in a stable condition.