We absolutely don’t have all of the info yet. Reports of multiple firearms including one on a tripod will make this interesting. Since aiming for a target wasn’t part of his plan two could have been used at either the same time or in quick sequence.
If you got the "tripod"description from the media, remember that they are blatheringly ignorant of gun facts.
(For many experienced shooters, a bipod serves far more frequently as a "kickstand" or prop than as a shooting aid... (Not everyone enjoys lying prone in the dirt, with the muzzle brake blast blowing sand into their eyes...)