Illinois native McFadden, Cassidy win wheelcair races

9:32 a.m.

Tatyana McFadden added to her Olympic glory. The Illinois native won the women's wheelchair division of the Chicago Marathon in 1 hour 49 minutes 52 seconds, adding to her three Olympic gold medals.

Josh Cassidy, 27, was the first to cross the finish line at the Chicago Marathon, winning the the wheelchair race in an unofficial time of 1:32:58.

Read more from Shannon Ryan in Chicago Breaking Sports

It's chilly -- but runners like it

7:59 a.m.

Thousands of runners poured onto Columbus Drive in the chill early Sunday morning, many wearing shorts and multi-colored running shoes.

An estimated 45,000 people are participating in the 2012 Bank of America marathon, which started with a siren around 7:30 a.m.

Most runners started out in a walk as the crowd approached the start line near Columbus and Monroe Drive.

Few seemed fazed by the 40-degree temperatures.

"We could not ask for better weather," said Alison Raitt, who has qualified for the Boston Marathon. The Los Angeles runner is hoping to run in the top 5 marathons, including Chicago, London, New York, London and Berlin.

"The training is hard, but the reward at the end is worth it," said Raitt.

Runners travelled from as far away as Russia and Ethiopia to run in Chicago. Isaias Castellanos said he hopes the flat course will make it easier for him to qualify for the Boston Marathon; he said he will need a time of 3 hours and 23 seconds, which would beat his personal best of 3 hours and 26 seconds.

"I'm hoping I'll make it here," he said, wearing a trash bag to shield himself from the cold. "But still, whether I make it or not, I'll still enjoy it."

-- Naomi Nix

Runner with a cause

7:07 a.m.

As thousands of runners hit the streets this morning with only Chicago's architecture to pass the hours a way, EJ Scott will be running the marathon blindfolded.