Q: Context: The mass shooting occurred between 10: 05 and 10: 15 p.m. PDT on October 1, 2017 (the third and final night of the festival). When the shooting began, country music singer Jason Aldean was giving the closing performance in front of an audience of about 22,000.

Question: who was playing during the las vegas attack?
Let's give stream of consciousness below
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 Jason Aldean.