ANTIOCH (KRON) — About 40 people, mostly children, reported having respiratory discomfort due to a “chemical exposure” at the Antioch Water Park, officials said.

At 2:29 p.m., emergency crews were called to the water park located at 4701 Lone Tree Way after getting reports of a child complaining of respiratory problems.

The exposure is contained to the water park, according to Contra Costa County fire captain George Laing.

Laing says that extra chlorine may have leaked into the pool.

As of 4 p.m., 10 to 15 people had been taken to the hospital.

Hazmat crews were called to determine the official cause.