The crash occurred on the Charlotte Motor Speedway track Saturday after a free daylong Vietnam Veterans Homecoming Celebration that attracted 62,500 people, The Charlotte Observer reported.
All three victims were rushed to hospitals, and the two drivers died soon after. The third victim remained hospitalized in critical condition late Sunday, the Observer said.
Concord police hadn't identified the victims but said none were from the Charlotte area.
Adrian Parker, the speedway's communications director, would not provide details on the collision, or say whether the speedway would review safety procedures or how it could prevent similar incidents. Parker said Concord police were investigating.
Shawn Lane of Willow Spring, who rode his motorcycle during the event, said he didn't see the collision but that motorcycle riders had been taking dangerous risks, including riding along a steep, banked turn, and he said some riders did not wear helmets.