They mentioned a white van. I'm guessing the occupant of the van may be using the van for concealment. His buddy drives him into position, and he fires out through a window or sliding door. They could have made some attempt to sound proof the van, so as to somewhat silence the shot.
He could have also have bench rest set up, as if it were a mobile blind for people hunting.
If this is the case I hope some citizens "dump" the van (roll it by hitting it in the rear quarter panel) then gang rank these aholes in public leaving a couple of convulsing and broken masses of meat for LEO to interrogate.
Montgomery County Police are looking for a white box truck that was seen leaving the scene of one of the deadly shootings on Thursday.
They are asking anyone with information to call them at (240) 777-2600.
The perps HAVE to be listening to the news. If they HAD used a white van, it's either been dumped somewhere, or painted another color by now. . .