The number of people sickened in an E. coli outbreak traced to a Chicago restaurant continues to increase, with 65 now confirmed. Twenty of the victims’ symptoms were so severe they were admitted to hospitals. Public health officials have not yet determined the root cause of the outbreak, which was traced to the Carbón Live Fire Mexican Grill location on 26th Street in the neighborhood of Bridgeport. The restaurant remains closed, according to Matt Smith, a spokesman for the Chicago Department of Public Health. logo Carbon Live Fire Mexican Grill“As part of our comprehensive investigation, we have taken and tested numerous samples from the restaurant and have tested staff,” Smith said Thursday. He did not say whether the department had the test results yet. It remains unknown when exactly the health department became aware of the outbreak. The department posted a news release about the outbreak July 1, but has not posted an update since then. The restaurant’s owners voluntarily closed the Carbón Live Fire Mexican Grill, according to the July 1 news release. A second Carbón Live Fire Mexican Grill on North Marshfield was also voluntarily closed, but the health department cleared it and the owners reopened. At least two Carbón Live Fire Mexican Grill customers who became ill and had to be hospitalized after eating food from the 26th Street location have filed civil lawsuits seeking compensation. In their lawsuits, the two victims reported eating food from the restaurant on June 22 and June 24, respectively. A third victim who was hospitalized with the outbreak strain of E. coli told Chicago’s CBS News affiliate she ate at the restaurant during the last week of June. Chicago public health officials continue to urge people to seek immediate medical attention if they ate food from the restaurant and later developed symptoms of E. coli infection. Generally symptoms develop within five to seven days of exposure, according to the Centers for Disease Control and Prevention. In otherwise healthy adults symptoms usually include severe stomach cramps, diarrhea that is often bloody, and vomiting. “Some infections are very mild, but others are severe or even life-threatening,” according to the CDC. “Around 5 percent to 10 percent of those who are diagnosed with STEC infection develop a potentially life-threatening complication known as hemolytic uremic syndrome (HUS). (To sign up for a free subscription to Food Safety News, click here.)