If the president says nothing about this, he has as much blood on his hands as the shooters. This is his lawlessness and he either needs to own it and stop or be blamed every time this happens. God bless the souls of the dead.
He'll say something. Probably something along the lines of "when we have a political climate where one party shows open hostility to people different than themselves and a campaign founded on division and hate, then frustrated people will lash out."
Then he'll blame the guns and instruct the FBI to sweep it all under the rug.