The salmonella outbreak at Heritage Corner Assisted Living facility in Ohio may be the reason behind the death of two residents, according to local reports. Health officials have not yet released an official cause of death.

There were 18 positive cases of salmonella starting at the end of May, officials said, and the outbreak appears to have ceased by June 10. The investigation is ongoing.

The county health district advised the facility to close the common areas for sanitization and serve meals in takeout containers. The areas were reopened after no new symptoms were reported for 72 hours.

The bacteria is the most common source of food poisoning in the U.S., causing one million illnesses and 380 deaths a year, the Centers for Disease Control and Prevention said. Symptoms of salmonella include diarrhea, cramps and fever, which usually develop 12-72 hours after infection. The elderly, infants and those with impaired immune systems are more susceptible to salmonella infections.