(MCT) — More than a dozen Chicago-area hospitals started their week overwhelmed with influenza cases, having to send incoming ambulances elsewhere at times as they dealt with what health officials have described as the worst flu season in nearly a decade.

On Monday, 11 Illinois hospitals had to go on bypass status, meaning they could not handle any more patients without life-threatening illnesses, said Melaney Arnold, spokeswoman for the Illinois Department of Public Health. Throughout Tuesday, four to eight hospitals across the state were on bypass at any given point.