In a statement, a city spokesperson said Mayor Thomas Schoenbein experienced a serious medical emergency at City Hall.
He was reportedly flown to the hospital, where he is receiving medical care.
"City leadership is in close contact with his family, and we ask the community to keep him in their thoughts and prayers during this time," the statement read, in part.
Officials said city operations remain fully functional, and the mayor's leadership team will continue to oversee municipal business during his recovery.