If I had to bet, I'd say she wasn't supposed to do it, unle…

If I had to bet, I'd say she wasn't supposed to do it, unless the snipers missed.

"When you come at the king you better not miss."

They had to make absolutely sure that he wouldn't survive the attempt.

When he was still alive after the first shot(s), she did what had to be done. Either consciously, or in a triggered state of mind control.