It was the second death reported at the Guangzhou Marathon.
Another runner, Chen Jie, 21, died of cardiac shock several hours after finishing a 10km race that was part of the event, the first of its kind in Guangzhou.
On Monday afternoon, both families gathered at the Guangzhou Sports Bureau, which was the major organizer of the marathon, to complain that poor organization led to both deaths.
In response, the organizing committee said both runners received prompt treatment and that there have been no issues related to medical fees, according to a press statement issued about two hours before Ding's death on Monday night.
"As the race was under way, the ambulance did not arrive at the site quickly. Medical staff had to rush to the scene and immediately conduct treatment," the statement said.
Local authorities organized more than 250 medical professionals, 380 volunteers and 20 ambulances to cover the event, according to the statement.
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