Satan's Little Helper (2004)

In the Oregon mountains, a pair of hunters encounter a machete-wielding killer in an abandoned church. Meanwhile, five campers arrive to examine some property one of them has inherited but are warned by the forest ranger not to venture forth. Soon after they set up camp, they begin hearing strange noises, encounter a mysterious singing girl and start disappearing one by one.

At the beginning of the film, we learn from one of the characters that earthworms can be called to the surface with electricity, but somehow it turns them into vicious flesh-eaters. Sure enough, a storm that night causes some power lines to break and touch the ground, drawing millions of man-eating worms out of the earth, and into town where they quickly start munching on the locals.