(CNN) -- Six children ages 1 to 7 have been hospitalized for severe gastrointestinal illnesses after swimming this month in an Alabama indoor water park, a state health official said Friday.
The children got sick after visiting the Opelika SportsPlex and Aquatic Center between June 12-18, said Dr. Mary McIntyre, medical officer of the Bureau of Communicable Disease at the Alabama Department of Public Health.
The indoor splash park was closed Friday but the park's other facilities remained open, a park official said.
Environmental officials will test chemical levels before the splash park will re-open, according to McIntyre. "We are continuing to work with the medical community to identify the extent of the problem," she said.
Five of the children have been transferred from East Alabama Medical Center in Opelika to the Children's Hospital of Alabama in Birmingham, where they were being treated with antibiotics, the official said.
In a statement, the department of public health urged parents whose children who may have visited the park to contact the health department if they suffer symptoms of nausea, vomiting or severe diarrhea.
Seven day-care centers took children to the Opelika SportsPlex and Aquatic Center for a day camp during the time frame officials have identified as when the water may have been contaminated, the health department said.
"We're recommending any children who did attend the splash park, until we can determine the full extent of the infection, not to swim in inflatable pools," McIntyre said. She added that such swimming could risk exposing other children to the bacteria.
Illnesses linked to pools are commonly caused by germs spread through contact with contaminated water, the department said in a news release. E. coli infections are caused by bacteria that can be found in foods and stool. Children often become infected after being exposed to others who are not toilet-trained.
"It's not uncommon for recreational water illnesses to occur, particularly in the summer, because a lot of people are in the pools," McIntyre said. "Children have a tendency to swallow water which is probably why we're seeing it in a younger group."
The health department warns people not to swim if they have diarrhea; to avoid swallowing pool or lake water; and to shower with soap before swimming so that germs and bacteria do not end up in pool water.