"All right, come a little ways away, out of the field of view of the rooms' windows, and watch for a couple minutes. Don't want him trying to sneak off while I try to get the keys from Merle's loyal footsoldier down there."
Solomon heads back to the desk, hurrying most of the way, so it's apparent he is in a rush, and gets the clerk's attention. He displays his badge, and wears a deadly serious, urgent expression. "Son, I need the keys to rooms 3 and 4... Now!" His bearing makes it clear that this is vitally important, and that further question are not necessary for the kid to think it's a good idea that Solomon should have the keys. If the kid gives them up, Solomon says, "Good man - you mighta just saved two lives. Until we sort this out and get everyone safe, you don't touch that phone or open your mouth, and you stay right here - Got it?" Then rushes out and back up to the rooms.
(ooc: Bluff +11, Intimidate +12. If the kid balks, we see how it goes from there. edit: By saying he mighta just saved two lives, Solomon is not implying a threat against the kid, but that two people in the room might be in danger. just to be clear.)