Two handguns with 30 round magazines would not have had to reload, especially if you consider the 9mm’s deserved reputation for overpenetration.
I have not heard any news that there are 30 round magazines for a 9 mm, only 15-17. Wow.
Even if he had 30 round magazines, that’s 60 shots. Reports indicate more than 60 casualties and fatalities. Even if he didn’t miss with a single shot (likely?), he had to have changed mags.