According to Orange County health officials, the individuals were infected after spending time in Anaheim or Disneyland between late August and October. The Los Angeles Times reports that two patients have died, but neither of these visited Disneyland. Nevertheless, 11 of the 15 infected had spent time at the park.

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Last week, Disneyland shut down two cooling towers that contained elevated levels of a bacteria known to cause Legionnaire’s. The disease is a lung infection caused by inhaling air that contains water droplets contaminated with the bacteria.

Since the cooling towers were closed, no further cases have been reported. Yet health officials cannot definitively point to the towers as the source of the disease and are therefore investigating neighboring areas as well.

Dr. Pamela Hymel, chief medical officer for Walt Disney Parks and Resorts, told the LA Times that while many of the patients having visited Disneyland “indicates a pattern” it does not “identify that specific location as the common source of infection for all cases.” She noted that “there is no longer any known risk associated with our facilities,” but did say the investigation is ongoing.