Magus soon heard the door of the van open, letting the water drain out.  He turned to see the leader of the robbers swing out, gun in hand.  The man called out, "No hitchhikers," and began firing on Magus.
"Rude," Magus said, ducking low under the shots.  He laid himself flat on the roof, making it almost impossible for the robber to see him while also giving him a relatively stable position that would allow him to stay on the vehicle.  He peeked out over the edge of the roof and sent a quick spurt of water at the gunman.  More than likely the attack would prove to be mostly a nuisance, but if it hit the gunman's hand, it might be enough to knock the gun out of the hand.  He began to mimic his adversary's tactic, shooting almost blindly at his attacker, but at least providing a distraction.  "You know, sooner or later, someone else is going to have to show up, and you won't be able to deal with them and me at the same time," he said, taking a few more shots at the gunman.

[@Flamelord]