Once Fred was certain that the Muggles were safe and locked into their boat house, he quickly worked to set a few shield charms around the perimeter of the building, grateful for the new distraction George had created. It only bought him a few seconds, though, and he set his mouth grimly as he finished, hoping that the spells were strong enough to hold back any of the Death Eaters from coming for the hidden Muggles.
Whirling around at the sound of the explosion, eyes flashing, he barely had time to think before he was leaping across the dock, following the flash of ginger hair that signaled his twin's running toward the source as well. Fred ducked and dove forward as he barely registered a flash of green zooming past him, landing hard on his side, on the dock, knocking the wind from his momentarily. Still, there was no time to even groan out in pain. He rolled, onto his front, partially hidden by one of the barrels, before sending another round of stunning spells toward the masked figures that had just saw him.
"Can never stay unnoticed, can we?" he muttered, frustrated and breathless, before shifting to pull out a few of the Decoy Detonators he had brought as well, setting them off, trying to buy enough time to at least get himself back on his feet.