Restaurant officials voluntarily closed Minneapolis Café Barbette over the weekend after the 20 cases of salmonella were reported. The city health department hasn’t determined what caused the food poisoning, but restaurant officials say they believe it’s isolated to one batch of chilled soup.

In April, restaurant inspectors found five critical violations serious enough to warrant a warning letter. A follow-up inspection three weeks later found all violations to have been corrected.

The restaurant has replaced their refrigerator.