Children were seen with breathing trouble as around 60 people have had to be decontaminated after an unknown chemical spilled into a water park pool, it is reported.
The problem began by a kids pool at Hurricane Harbor Splashtown, in Texas, where first a lifeguard became sick and then others also began feeling unwell.
The Spring Fire Department responded to the call around 3 pm at 21300 Interstate 45 in Spring.
"What began as a fun family day turned into very much a nightmare for many families," Harris County Judge Lina Hidalgo told a press conference.
She said children started walking out of the pool with respiratory issues.
Officials in protective gear came to monitor the air but so far the authorities are not sure if the spill came from a leak.
Hidalgo has asked for people to avoid the area.
She tweeted: "Our HAZMAT team and pollution control department are providing support to @springfdtx.
"No indication of air quality or chemical leaks in the surrounding area at this time but please avoid the area if possible. We will be sharing further updates shortly."
People affected have reportedly told of having minor skin irritation and inhalation trouble.
The most serious case involved a child who was rushed to Texas Children's Hospital The Woodlands but is now stable, said Hidalgo.
There have been 36 people who have said they didn't need hospital treatment while 20 others were taken to Memorial Hermann.
