The Public Health Agency of Canada is warning the public about an outbreak of a potentially deadly form of E. coli after at least 24 people became infected and five of them ended up being hospitalized.

The 24 cases of Escherichia coli O157 occurred between July 12 and Aug. 8, with the “peak of illnesses” reported between July 25 and Aug. 1, according a statement from PHAC. The source of the illnesses has not yet been identified and the investigation is ongoing.