The number of confirmed cases of Legionnaires' disease at a Social Security Administration building housing 1,200 workers has reached nine, officials said. "In addition, we are working on two other suspected cases," said Scott Lewis, spokesman for the state Department of Health Services. One of the latest confirmed cases is that of Margaret Thomas, 48, who remained comatose Wednesday at Brookside Hospital in San Pablo. "She is not conscious and is in critical but stable condition," said hospital spokeswoman Susan Peterson. The nine also include Rosalind Sheffield, 37, a janitor who died Sept. 9. It was learned Sept. 12 she had the disease, which is caused by a bacteria inspectors believe to have been centered in the ventilation system of the six-story building. The building was closed Sept. 12 and will remain closed at least through this week, until it is certified as safe. The building is being disinfected, with the cleanup including the removal of water from its cooling system towers. Water is considered the mostly likely source of the bacteria Legionnella pneumophilia that causes the disease.