The first incident occurred at around 5 p.m. at Ohio Street Beach as emergency crews were called there for a man in the water, Chicago fire officials said. He was pulled out and transported to Northwestern Memorial Hospital in critical condition.
It was not immediately clear how the man came to be in distress in the water, or any further circumstances surrounding the incident.
Just hours later at around 10:30 p.m., a 65-year-old man was rescued at 31st Street Beach. Police said he was walking on the pier when he fell in.
The man was transported to the hospital in critical condition for trauma to the body, police said. Detectives are investigating.
Meanwhile, according to the Great Lakes Surf Rescue Project, at least 24 people have drowned in Lake Michigan so far this year. That includes an off-duty firefighter who drowned last month off of 31st Street Beach.
The organization saying it noticed a spike in drownings back in July. They said it's a big concern since the beaches are still officially open for two more weekends.