 
 <translate> To answer this question, we should know that: When the shooting began, country music singer Jason Aldean was giving the closing performance in front of an audience of about 22,000.
So, the answer is country music singer Jason Aldean. <ibo> Iji zaa ajụjụ a, anyị kwesịrị ịma nke a: Mgbe a malitere ịgba égbè ahụ, onye na-agụ egwú country bụ́ Jason Aldean nọ na-eme ihe ngosi mmechi n'ihu ihe dị ka mmadụ 22,000. Ya mere, azịza ya bụ onye na-agụ egwú mba bụ́ Jason Aldean. 