Doctors say sudden death typically occurs in 1 in 100-thousand people so to have two deaths among 25-thousand runners is rare.
It was a perfect running day that turned tragic. Two men - a 21-year-old and a 40-year-old - collapsed by the finish line and died.
I met with Dr. Alfred Bove a cardiologist at Temple and past president of the American College of Cardiology to talk about what may have sparked the problems.
It was first reported both died from heart attack.
"You know a blocked artery to the heart, a sudden lack of blood flow to the heart muscle," says Dr. Bove.
But he says for a 21-year-old that is unlikely.
More likely for a young person is an unknown heart abnormality.
Exercise can aggravate it- sparking the heart to fall out of rhythm but it can also happen at random.
As for the 40-year-old, it could be a similar problem, or a heart attack caused by clogged arteries.
That's what happened to 46-year-old Ray. He spent several months doing cardiac rehabilitation after suffering a heart attack during a Mud Run this summer.
"Very suddenly, I just couldn't grab my breath," he says.
Fortunately, emergency medical crews were close by. Ray was transported to the hospital and was treated just in time.
He had no symptoms before the race, and was in top shape. He tells others now to get a physical before entering any sports competition.
"An ounce of precaution is worth a pound of cure," he notes.
Dr. Bove recommends young people also see their doctor.. And go through the American Heart Association's checklist. Older athletes should have a more comprehensive exam.
"If someone at 40 wants to start running a marathon, I think it's important they get a check up, get a cardiogram, and get the blood tests to assess risk for a heart attack," says Dr. Bove.
Experts say unfortunately with young people many heart problems go un-detected.
There is still controversy whether younger athletes should be routinely screened for heart problems with an EKG. Right now, that is not the standard.What is your risk of heart problems? Take the American Heart Association LifeCheck at www.mylifecheck.org.