E. coli cases in Washington and Oregon have forced Chipotle to temporarily close 43 of its locations in the two states, over the weekend.

The Washington Post reports that there have not been any deaths related to the outbreak. There have been as many as 22 cases across states, leaving eight hospitalized, according to Washington health officials.

In a statement, Washington Department of Health has linked the outbreak to food served at Chipotle, the exact food or source of contamination has not yet been discovered. The cause remains under investigation.

Eight restaurants have potential links to the outbreak, but 43 have been closed by Chipotle, as a cautionary measure, according to a spokesperson for the restaurant chain.

The spokesperson said that the restaurants will reopen in pace with the investigation. The investigation is Chipotle’s top priority.

The populations that are at the greatest risk of illness from E. coli are children and the elderly. Strains of the bacteria are known to cause fever, vomiting, and diarrhea.

Officials expect the number of Chipotle connected E. coli cases to increase through the week as the investigation continues. Following the outbreak, shares in the restaurant dropped five percent, Monday.

Previously, Minnesota Chipotle locations were faced with a salmonella outbreak that sickened 64 people. The outbreak was found to be caused by tomatoes used in the restaurant.