UPDATED: 7 Hospitalized After Chemical Spill at Signal Bay Waterpark

Signal Bay Waterpark was evacuated and seven swimmers were treated after a chemical spill in the pool Saturday afternoon.

It happened at about 1:30 p.m. when lifeguards noticed a "chemical smell" coming from the water and saw a yellow patch forming in the pool, Manassas Park city manager Jim Zumwalt said about an hour after the incident.

E-911 was called and the pool was immediately evacuated, he said.

One child complained of breathing problems and was treated on scene by a lifeguard and only that lifeguard, despite reports of that person being helped by another swimmer, Manassas Park Department of Parks and Recreation Director Catherine Morretta said.

She wasn't on scene during the incident, but was told by senior employees that at least one swimmer was vomiting, but it is not clear if that was because of the chemical, Morretta said. 

Close to 300 people were at the park at the time of the incident and everyone was evacuated in an orderly fashion, she said.

Employees followed the rules and procedures in dealing with the matter, she added.

Six swimmers were taken by medics to Prince William Hospital in Manassas for treatment while one other person went to the hospital on their own, Zumwalt said.

A hazmat team checked the pool to make sure there were no detectable chemicals and then turned the pool over to the Manassas Park Police Department for further investigation.

The pool will be closed Sunday and will reopen after a pool equipment expert familiar with the facility has inspected all of its chemical handling equipment.

The inspection will likely take place Monday when the pool is closed anyway, Morretta said.

The director said she can't  even begin to speculate on what went wrong.

It is not immediately clear what type of chemical caused the problems in the pool, but the most likely culprit is chlorine, a cleaning agent used in pools, Zumwalt said.

Manassas Park Fire Department,  Manassas Park Police Department, Buckhall Volunteer Fire Department and Prince William Fire Department Hazmat Team respond to the incident at Signal Hill Park.  Assistant Chief Tim Mahoney of the Lake Jackson Volunteer Fire Department served as incident commander on the scene.