Three people in Surrey, B.C. have been hospitalized with Legionnaires’ Disease, a severe form of pneumonia that develops after being infected by the Legionella bacteria.

“We still don’t know where they were infected, but it’s suggestive of a local source,” Dr. Aamir Bharmal of the Fraser Health Authority told CTV News, adding that the source is likely in the Guildford area. Bharmal said symptoms would typically appear between two and 10 days after exposure if the infection develops.

Bharmal explained the bacteria is found naturally in soil and natural water sources, but it can grow in human-made water systems such as air conditioning, swimming pools and plumbing systems and become aerosolized, or inhalable. The Public Health Service of Canada points out it cannot be transmitted between people.

“Most people don’t get sick from Legionella, but people who have chronic health conditions or who are elderly or smokers or immune-compromised, they may eventually get a type of pneumonia called Legionnaires’ Disease,” he said.

Bharmal is urging people with those risk factors who’ve been in the Guildford area of Surrey in the past 10 days and have symptoms of pneumonia (fever, fatigue, cough, shortness of breath) to seek medical attention and possibly testing for Legionella. At this point, officials aren’t suggesting at-risk people to avoid Guildford.

Legionnaires’ Disease was responsible for 12 deaths in Flint, Mich., in 2014 and 2015. An outbreak during that city’s water crisis infected close to 100 people.

More recently, two cooling towers at Disneyland were shut down last November, after 15 cases of the disease and two deaths were reported in Anaheim.

Fraser Health typically sees about six cases per year of Legionnaires’ Disease. The health authority says it’s aware of fewer than 10 cases associated with the current “cluster” of infections in Guildford.

With files from CTV Vancouver’s Nafeesa Karim