CHICAGO | One worker has died and two others are hospitalized after they were overcome by an ammonia-like vapor at Chicago's Blommer Chocolate factory.

Chicago Fire Department spokesman Richard Rosado says firefighters were called to the factory just west of the city's downtown at about 11 a.m. Sunday.

He said the employees were overcome as they worked with a powder used to make chocolate that gave off a strong vapor.

One worker is at Northwestern Memorial Hospital in critical condition, while the second is in fair condition at the University of Illinois Medical Center.

The Cook County Medical Examiner's office is not releasing the dead worker's name. Autopsy results are expected Monday.

Messages left for a Blommer spokeswoman were not immediately returned Sunday.