Toby Keith and Garth Brooks headline concert benefiting Oklahoma tornado victims

Thousands of people packed the University of Oklahoma's stadium on Saturday for a concert benefiting the state's tornado victims.

The Oklahoma Twister Relief Concert in Norman was headlined by a bevy of country stars, including Garth Brooks, Toby Keith, Willie Nelson and Trisha Yearwood. The sold-out concert drew an estimated 65 thousand people, with proceeds going to the United Way of Central Oklahoma, an organization established to aid tornado and storm victims, reported USA Today.

A separate benefit concert held last month hosted by OK-native Blake Shelton raised over $6 million in donations and pledges. Brooks took the stage Saturday afternoon to perform "Two of a Kind, Workin'" and "Papa Loved Mama." Trisha Yearwood, his wife, joined him for a duet on "In Another's Eyes.""God bless you, Oklahoma!" she said.

Nearly 1,300 concert-goers were treated for heat-related problems, most of them receiving minor treatment at cooling stations or at a medical facility within the University. 170 required more extensive treatment and 21 were taken to hospitals, Kelly Wells, spokesperson for Norman Regional Health System told NBC News.