Two runners died while participating in the Rock ‘n’ Roll Marathon Sunday, The News & Observer reported. 

The runners, whose names were not released as of press time, collapsed close to the finish line and died despite rapid treatment from the event’s medical teams. 

Both men were in their 30s with pre-existing, undiagnosed heart conditions, The N&O reported. 

“We regret to confirm that two participants passed away at today’s half-marathon,” Dr. P.Z. Pearce, the event’s medical director, told The N&O. “We are greatly saddened by these tragic losses and our prayers go out to the each of the runner’s family and friends.”

Both men were taking part in the 13.1-mile half-marathon.

Dr. Jeff Bytomski, a physician at Duke University, told The N&O that cardiac deaths are the most common reason for deaths during races.

“It’s just an inherent risk at these races,” Bytomski said. “It’s still a very low risk, but it happens.”

About 12,500 runners attended from 49 different states for the 26.2 mile marathon and 13.1 mile half marathon that ran through downtown and western Raleigh.