A Wisconsin marathon was halted Sunday after several runners and walkers experienced heat-related problems and required medical attention.

At least 18 people went to area hospitals - most had heat stroke and were treated and released. One person was admitted to St. Mary's Hospital Medical Center, said Lisa Malak, hospital spokeswoman.

Cellcom Green Bay Marathon director Sean Ryan told The Associated Press that he did not have immediate information on the number of people treated by medics at the race itself.

Ryan also said officials knew temperatures would climb when the race started at 7 a.m. but hoped a combination of wind, medical resources, ice and water stops would help keep problems in check.

"The temperatures climbed rapidly," Ryan said. "Within a matter of hours, the situation began to overwhelm medical resources."

The race was officially shut down at 9:35 a.m. In a statement issued later Sunday, marathon medical director Jeremy Metzler said: "Runner safety is our first priority and we had to make that call for our runners."

A total of 7,411 people started the marathon and half-marathon, and 49 percent finished before the race was stopped, most of them in the half-marathon. Only 10 marathoners finished with official results based on gun time, Ryan said.

Marathon media coordinator Tammy Vandenbusch said once the course was shut down, runners were urged to get on shuttle buses, but some kept running.

J.P. Conroy, a half-marathoner from Winona, Minn., told the Green Bay Press-Gazette he stopped running and started walking.

"I didn't want to be that person. I didn't want to take a chance," he said. "People were lying down with ice packs on them on Mile 7 and around Mile 11."

The newspaper reported that David Tuwei won the men's full marathon in 2 hours, 27 minutes, 11 seconds.

The National Weather Service predicted a high of 82 degrees in Green Bay on Sunday. The temperature was 70 degrees with 63 percent humidity when the race started.

"It was a tough day for running," Vandenbusch said.

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