By the light of the few fires that were still burning, he could see
people running away into the woods, fleeing something that was
moving across the field toward them, something that was emitting
odd flashes of light and noises like gunfire. Loud jeering, roars of
laughter, and drunken yells were drifting toward them; then came
a burst of strong green light, which illuminated the scene.

people running away into the woods

A crowd of wizards, tightly packed and moving together with
wands pointing straight upward, was marching slowly across the
field. Harry squinted at them. . . . They didn’t seem to have
faces. . . . Then he realized that their heads were hooded and their
faces masked.

A crowd of wizards

More wizards were joining the marching group, laughing and
pointing up at the floating bodies. Tents crumpled and fell as the marching crowd swelled. Once or twice Harry saw one of the marchers blast a tent out of his way with his wand. Several caught
fire. The screaming grew louder.

More wizards were joining