I cannot imagine how Hassan was able to fire 100 rounds, wound or kill 46 individuals, reload 4 or 5 times, within 5 minutes. I don’t believe I could do it, even with stationary targets.
A hundred rounds in five minutes would be easy.
You can empty a 20 round magazine in about 10 - 15 seconds. 100 rounds in 5 minutes wouldn’t even be “hurried”.
It does seem passing strange that he wasn't rushed and bashed with a chair, desk lamp, something while focusing in one direction, or was reloading. Standard magazine for the FN are only 20 rounds, although 30 are available. So he'd have to reload 4 times. Now a mag change doesn't take long, but long enough to run up and bash him from behind.