Chicago ? In a race run in scorching heat that left one man dead, Kenya’s Patrick Ivuti won the Chicago Marathon by a fraction of a second Sunday. At least 49 runners were taken to hospitals and 250 treated at medical stations.

Ivuti leaned at the finish line to edge Jaouad Gharib of Morocco by 0.05 seconds. The winner finished 2 hours, 11 minutes, 11 seconds. Ethiopia’s Berhane Adere rallied to defend her women’s title successfully. She finished in 2:33:49.

The 88-degree heat and sweltering humidity were so draining that organizers shut down the second half of the course four hours after the start.

Chad Schieber of Midland, Mich., 35, collapsed while running on the South Side and was pronounced dead shortly before 1 p.m. at a Veteran’s Affairs hospital, the Cook County medical examiner’s office said. An autopsy was scheduled for today.

George Chiampas, the race’s medical director, said witnesses reported seeing Schieber collapse and become unresponsive. “It sounds like he lost his pulse very fast and died on the race course,” Chiampas said.

Race director Carey Pinkowski said organizers were concerned that emergency medical personnel wouldn’t be able to keep up with heat-related injuries.

“We were seeing a high rate of people that were struggling,” Pinkowski said. “It was just a brutally hot day.”

Helicopters hovered over the race course while police officers shouted through a bullhorn and warned runners to slow down and walk.

About 10,000 of the 45,000 registered runners chose not to race in the heat despite more mist stations, cooling buses and water-soaked sponges, while another 10,934 started but didn’t finish, officials reported.

Lori Kaufman, a runner from St. Louis, said she was told to start walking at mile 14. She said the fire department turned on hydrants to hose people down along the course.