FOND DU LAC, Wis. — Fire officials in Fond du Lac say a carbon monoxide leak sickened workers Monday at a Quality Packaging warehouse.

Crews were sent around 2:30 p.m. on a report of a possible carbon monoxide leak and workers feeling ill. Fire crews began to treat several workers. Alliant Energy also was at the scene and along with fire crews detected elevated levels of carbon monoxide in the warehouse.

The building was evacuated and ventilated. Some workers refused medical attention, but eight patients were taken to hospitals in Fond du Lac and Waupun.

Fond du Lac Fire Chief Peter O'Leary said the leak apparently came from a forklift used in the warehouse.