Two runners died while competing in the 2011 Philadelphia Marathon on Sunday morning.
Philadelphia police say the two people collapsed during the race and suffered heart attacks.
Police spokeswoman Officer Jillian Russell told The Associated Press a 21-year-old Asian man collapsed at the finish line while a 40-year-old white man collapsed a quarter-mile before the end.
The two were taken to Hahnemann University Hospital, where both were pronounced dead on arrival from apparently heart attacks.
We are deeply saddened and our thoughts are with their families and friends, executive director of The Philadelphia Marathon Race Weekend Melanie Johnson said in a statement.
The names of the victims are not being released as relatives are still being notified.
According to fire officials, at least ten others were rushed to the hospital on Sunday.
More than 25,000 runners participated in the Philadelphia Marathon, which had street closures for the race, as the Philadelphia Inquirer said three times as many people are expected to watch as spectators.
While the day was pleasurable for running in the mid 50's, SB Nation reports the ideal temperatures for marathon running are in the upper-to-mid 40's, as warm temperatures could lead to overheating and dehydration.
The Philadelphia Marathon officially began on Sunday but unofficially kicked off on Saturday with the running of the 5 mile Rothman Institute 8k for amateurs. The full and half marathons on Sunday are 26.2 miles and 13.1 miles, respectively.
The official Twitter account for the Philadelphia Marathon did not mention the deaths of the two runners on Sunday, but did live tweet results and photos of the race.