The Twin Cities Marathon was canceled Sunday morning just hours ahead of the race due to the hot weather conditions forecasted for the day, organizers announced.

“All week, we knew that it was going to be a really hot, really humid day,” said Twin Cities in Motion Senior Media and Communications Manager Charlie Mahler. “Had the biggest volunteer medical team we’d ever amassed, based on records we have for a marathon weekend. Then when forecast temperatures rose overnight, we just knew that we had crossed the line from a red flag race to a black flag race and we just weren’t gonna put 20,000 people at risk.” 

According to a news release, both the Medtronic Twin Cities Marathon and Medtronic TC 10 Mile races were canceled because of ‘EAS Black Flag’ weather conditions, which stands for ‘Extreme and Dangerous Conditions.’

“The latest weather forecast update projects record-setting heat conditions that do not allow a safe event for runners, supporters and volunteers,” said Twin Cities In Motion in a press release.

“Extreme heat conditions can tax both runners and our emergency medical response systems,” the organization noted in a news release. “We ask the entire running community to come together for the safety of everyone involved.”

A spokesperson for the Twin Cities Marathon said this is the first time hot weather has canceled the entire event.

“We’ve had to cancel other events due to heat or other weather concerns, but never the marathon,” the spokesperson said.

Despite the official cancellation of the event, dozens of people took off from the starting line Sunday morning.

Race officials say about 20,000 runners were registered for the race.

One runner at the starting line who didn’t realize the race was canceled spoke about the surprise she felt after hearing the news.

“I’m more shocked right now than disappointed,” said Jenny Breen, a runner from Minneapolis. “I can’t even imagine people for whom this was a huge, huge race. I mean I fortunately get to race regularly, so I’ll get over it, but it’s really sad. Really sad.”

Twin Cities in Motion said they will be giving runners an update Thursday about possible credit for the canceled event.

More information from Twin Cities in Motion can be found here.