NORMAN, Oklahoma - Oklahoma native and country music super star Carrie Underwood has been added to the line-up of Toby Keith's sold out Twister Relief Concert in Norman; but she won't appear on stage with the other singing stars.

Underwood will perform via satellite at the July 6 concert. Keith, Garth Brooks, Trisha Yearwood, Willie Nelson and Sammy Hagar will perform at the University of Oklahoma's Gaylord Family – Oklahoma Memorial Stadium. Tickets for the concert went on sale June 21 and quickly sold out.

All proceeds will go to the United Way of Central Oklahoma's efforts to help those affected by the deadly Oklahoma tornados in May.

Organizers say while there are no tickets available right now, they may release more tickets later.