The sinkhole even devoured one of the stadium's light poles, KMOV reported.
A construction materials company said an underground mine collapsed at about 10 a.m. at Gordon Moore City Park.
Local parks and rec officials estimate the sinkhole to be 100 feet wide and 30 feet deep.
Afterward, the park was off-limits, while experts examined the damage and planned repairs. Some events were canceled.
No injuries were reported.
A security camera captured the moment the sinkhole opened up, swallowing the light pole, turf, and more.