Fire Chief Samuel Pea praised Houston Fire’s swift triage and transportation of victims in a post-incident statement.

Twelve persons, including at least seven children, have “possible accidental ingestion” as a result of a chlorine discharge at a lazy river pool in Houston, Texas.

Sam Pea, the chief of Houston’s fire department, reported on Twitter on Saturday that 12 individuals had to be taken from the Club Westside fitness center to a nearby hospital due to what appeared to be “over-chlorination” of a pool.

Before 6 p.m. local time on Saturday, Pea urged the community to “stay clear of the area due to ongoing emergency operations” before confirming more than two hours later that the situation was “under control.”

Before 5 o’clock local time, authorities responded to reports of the spill.

He followed up with, “Cause appears to be an over-chlorination of the pool(s),” on Twitter. “Good job by @HoustonFire in triaging & transporting people quickly.”

“Exposure to over-chlorination can trigger asthma, nausea, and skin & eye irritation,” Pea continued.

Later, according to the Houston Fire Department, 7 children and 3 adults were taken to the hospital, some by “private vehicle.”

The age ranges of the other two patients are unknown.

On Club Westside’s website, the facility is described as having “a 32-person Jacuzzi, kids’ waterslide, and three pools heated year-round.”