Twenty-three children were rushed to a hospital after falling sick from eating fresh and boiled cabbage during a cooking class at an elementary school in Hirano Ward, Osaka, police said.

The fifth-graders were comparing the taste of fresh and boiled cabbage. The cause was not immediately known but the symptoms were not serious.

About 40 children were attending the cooking class at Hirano Elementary School. After eating cabbage, 10 boys and 13 girls began feeling sick and the school set up a temporary first-aid center. At least three ambulances and two fire engines took the children to the hospital.

"I thought some (big) incident broke out because firefighters and the police came," said a woman whose 10-year-old daughter goes to the school. "I haven't got much information, but am relieved to learn the symptoms were not serious."