Drugmaker GlaxoSmithKline (GSK) shut down a North Carolina plant Tuesday after testing at a cooling tower found bacteria that cause deadly Legionnaires' disease, a company spokeswoman said.

The manufacturing plant — which produces inhaled medications — in Zebulon, about 25 miles east of Raleigh, was closed after routine testing found the bacteria in a standalone cooling tower at the plant. About 400 of the 850 employees who work in Zebulon were told to stay away until the towers are cleaned, said officials for GSK, which is based in London.

The company said in a statement that the cooling tower "does not come into contact with product manufactured at the facility."

GSK did not respond to questions about whether there was any risk of indoor exposure to employees or medicines from water droplets that could carry the bacteria.

"We are trying to gather information on what the situation is," spokeswoman Jenni Brewer Ligday said. Testing is conducted every three months, and the company was seeking "more details on whether product has been impacted and, if they have, what is our procedure in place to handle that."

The plant produces inhaled drugs like Advair, a drug for asthma, and contracts with other pharmaceutical companies to produce their drugs.

The Food and Drug Administration was checking into reports of the bacteria's discovery, and a spokesman said questions should be directed to GSK.

The same bacteria, found in cooling tanks in the Bronx in New York City, has caused 12 Legionnaires' disease deaths this summer. No new cases have been reported in the Bronx outbreak since Aug. 3. An inmate at Rikers Island was diagnosed on Monday, according to media reports, but officials believe that case is not connected to the Bronx cluster.

The Centers for Disease Control and Prevention says about 8,000 to 18,000 Americans are hospitalized with the illness annually. Legionnaires' disease, a severe kind of pneumonia, is contracted by breathing in mist containing the bacteria. It is not contagious, according to the CDC.

Wire services