Two women were overcome by foul-smelling fumes at Brea City Hall on Wednesday, which in turn forced the evacuation of about 200 employees while a hazardous-materials unit swept the building to find the source of the odor.
The team collected samples into the evening after the women, one of whom is pregnant, were treated at area hospitals and released. Authorities said a possible source of the fumes was a leak from the city's photo lab in the public relations department.
Four other employees were treated at the scene for eye and throat irritation.
"They complained of a rotten-egg-type odor," said Dave Huffman, division chief of the Brea Fire Department.
Six fire engines and six ambulances were dispatched after a woman complained about a strange odor about 3:30 p.m. A duty battalion chief who happened to be at City Hall at the time was escorting that woman back to her work area to investigate the odor when she collapsed.