 -- At least 22 people, most of them children, reported symptoms such as nausea, dizziness and vomiting from an unknown cause at a Colorado recreation center this weekend, according to a local fire chief.

Lafayette Fire Chief David Friedel, in Lafayette, Colorado, told ABC News today that the cause remained undetermined.

"Thought it might have been chlorine" leak, Friedel said. "Hazmat crews couldn’t detect anything like that."

Friedel said 22 people came down with nausea, dizziness and vomiting after entering a pool at the Bob L. Burger Recreation Center on Saturday.

Joe Malinowski, Environmental Health Division Manager for Boulder County Public Health, said that no air contaminants were found on Saturday and that they were examining if something had gone wrong with the chlorination system. He said the health department will go to the pool today to examine if it is safe to reopen.

A man identified by his first name Mike told ABC affiliate KMGH-TV that his eyes started burning shortly after seeing people come out from the pool area.

"People were coming out coughing and choking and having a hard time breathing," he told KMGH-TV. "I started checking on them to see if they were all right."

Friedel told ABC News that everyone taken to area hospitals was released by Sunday evening.