UPDATE: This statement was released shortly after 3:30 p.m. Monday, July 14, by Muskegon County Sheriff Dean Roesler relating to the statements made about the alleged cause of the gas cloud at the amusement park:

"A short time ago an official from my office made a statement to various media sources that the cause of the July 11, 2014 Haz-Mat incident at Michigan's Adventure Amusement Park had been officially determined as human error and then went in to detail how this occurred. While human error remains 1 possibility, the final determination by experts HAVE NOT been made. There is a continuing investigation by qualified officials including interviews, data review and testing, to determine the cause. I apologize on behalf of my Office for any confusion this may have caused. Once the cause has in fact been determined, that information will then be released."

MUSKEGON COUNTY, MI – It appears an apparent miscalculation by a Michigan's Adventure employee on Friday, July 11, caused the chlorine gas cloud that affected around 60 people who became sick from a mixture of commonly used household pool chemicals.

That's the early verdict on the cause of the midday July 11 mishap at the park, according to the Muskegon County Emergency Management Director Dan Stout II, a Muskegon County Sheriff's Office sergeant.

Stout said the incident may have been caused by "human error," but a more official determination is in the works.

The investigation is in the preliminary stages and no final determination into the cause has been made.

Muskegon County Hazmat Chief Steve Lague said that Stout's statement is not correct.

"The investigation hasn't really even started yet. I'm sure it has with Michigan Adventure's, but not outside agencies," Lague said.

Lague said it's premature to come up with any real theory about how the incident occurred at this time. Muskegon County Hazmat and Muskegon County Emergency Service Management won't be part of the final investigation.

Stout said a maintenance person at the park who does testing every hour at the pool put in incorrect calculations to regulate the amount of chemicals in the pool.

"There was human error in those calculations and that's what caused the chlorine gas cloud," Stout said.

The gas cloud was formed by two of the chemicals mixed together: muriatic acid and sodium hydrochlorite, two common household pool chemicals, that combined and created a hazardous "small chlorine gas cloud" at about 4:07 p.m. that Friday.

Stout said 63 people were treated in about a two-hour time frame. All those affected have recovered, Stout said.

Eleven of those people were lifeguards trying to assist those in the pool area, he said. It wasn't clear Monday whether the park would be subjected to fines or penalties in connection to the incident, Stout said.

"The park hasn't finished its own investigation. They will send me their report they are writing up for the state and then the state will go from there and do its assessment," Stout said.

In the meantime, Stout said he is proud of the first responders who arrived quickly to the scene and worked efficiently.

"Everyone worked well together and came together as team," he said.

Several fire departments, ambulance services and police agencies responded to the scene. The theme park did "an excellent job" responding to a chaotic situation as well, Stout said.

"The lifeguards noticed people were coughing in the wave pool and saw the smoky gas coming out of their vents. They jumped in and grabbed people out of the pool," he said.

In an official statement, the park said lifeguards and emergency personnel responded to the emergency after it detected high chlorine levels at the Tidal Wave pool. Several fire officials also responded to the scene as well as the local Hazmat team.

Michigan's Adventure staff had been conducting an internal audit to figure out what happened at its Wildwater Adventure site, which features slides and wave pools. The facility, located at 4750 Whitehall Rd., is the largest amusement and water park in Michigan.

Heather Lynn Peters covers police and fire, and writes a statewide food column, The Spunky Kitchen, for MLive/Muskegon Chronicle. Email her at hpeters@mlive.com and follow her on Twitter @HLPNEWS.