Updated

At least 30 people were treated for vomiting and diarrhea as the Special Olympics national games ended Friday, and health officials warned authorities in other states that the illness could spread as people return home.

An estimated 30,000 people attended the six-day event in Ames.

"Some people have already left," said Mary Mincer Hansen, director for the Iowa Department of Public Health.

She said state health officials have contacted other health departments across the country and are still unsure why coaches, fans and athletes are feeling sick.

At least 10 have been hospitalized, and the health department has set up an area for others at an Iowa State University recreation center. Hansen said it was a precaution to keep hospitals from getting overwhelmed.

The health department questioned those affected and called in food inspectors to investigate possible causes. Tests have been taken and results are expected Saturday, Hansen said.

The first sicknesses occurred Friday morning but the health department was not informed until after noon, she said.

"With that large a crowd, people thought there would be some people getting sick," Hansen said. But when more athletes, coaches and fans kept getting the same symptoms, health officials took action, she said.

Special Olympics officials would not comment Friday night.