Investigators were working to identify the person whose body was pulled from Lake Michigan after being spotted about 12 miles from shore, authorities said Monday.
At least 35 people have drowned in Lake Michigan so far this year, according to the Great Lakes Surf Rescue Project, which tracks drownings.
Plummer joined the Fire Department Dec. 1, 2020, having only recently marked one year as a Chicago firefighter. Plummer had been assigned to Engine 94 located in Portage Park.
Killed in the accident were Margie and Don Vardahoe, a Georgia couple on a cross-country trip to mark their 50th wedding anniversary, and Zachariah Schneider, 28, a software developer from Illinois.
Officials said nearly a dozen fire departments responded to Sunday's fire in the Will County village of Beecher, but by the time the flames were doused St. Paul's Lutheran Church was in ruins.
The situation began just before 1 p.m. when a 911 caller reported three people struggling in the water. They were found hanging onto a breakwall and pulled out. Roughly an hour later, crews on the beach found "unclaimed belongings" of another person, which sparked the search for the fourth swimmer.
The victims included a 30-year-old Chicago man and a 67-year-old Michigan man.