Former Chicago Mayor Richard M. Daley is undergoing tests in the intensive care unit at Northwestern Memorial Hospital this weekend, after feeling ill on his way home from a business trip Friday night, according to a spokeswoman.

Daley, 71, was taken to the hospital by ambulance Friday night after returning to Chicago from a legal conference in Arizona, said Jackie Heard, a spokeswoman for Katten Muchin Roseman, LLP,  the law firm where the former mayor now works.

Heard said that Daley is awake and alert, but did not offer specifics as to his symptoms or his current condition.

“Mayor Daley’s not one to not feel well often, so just as a precaution the ambulance was there,” Heard told WBEZ Saturday afternoon. “He did walk from the plane to the ambulance.”

Daley spent Friday night at the hospital and is currently undergoing monitoring and evaluation at NMH. His family has been visiting in between tests, according to a statement released to reporters.

Daley has kept a busy schedule since stepping down in 2011 after 22 years as Chicago’s mayor, Heard said. 

His illness came the same day that his nephew, Richard J. Vanecko, pleaded guilty to involuntary manslaugther for the death of another man in a fight outside a bar in Chicago’s Gold Coast neighborhood in 2004.