More than Two Dozen People Sickened in CA Hazmat Incident

California fire officials are trying to determine the cause of a hazardous materials incident at a commercial building that sent nine people to the hospital and sickened nearly 30 others Thursday.

The incident happened at around 8 a.m. after an individual began experiencing chest pains at Philips North America, a dental products company in Ontario, The Press-Enterprise reports. Hazmat units and 10 ambulances from the Ontario and San Bernardino County fire departments were called in after other employees began feeling sick and experiencing breathing problems.

Crews began trying to determine what was causing workers to become ill, as well as trying to find the source of the inrritant. Monitoring equipment registered some "low-level hits" in the facility, but firefighters couldn't isolate the source of the problem, Ontario Battalion Chief Scot Roeber told The Press-Enterprise.

A total of 28 workers reported experiencing breathing problems, and nine people were taken to area hospitals with respiratory irritation, according to the Ontario Fire Department. None of the injuries were considered life-threatening.

The building eventually was ventilated, and the company determined the air inside was free of any irritants, The Press-Enterprise added.