While the creatures in "The Mist" aren't technically worms, they are large, tentacled, and monstrous creatures that emerge from a mysterious fog. They attack and kill people in a terrifying and brutal way.
Other films that might fit your description, but aren't quite the same, include:
* "Tremors" (1990) - This movie features giant, subterranean worms called "Graboids" that attack people in a small desert town.
* "Slither" (2006) - A meteor crashes in a small town, and a parasitic alien worm takes over the town's inhabitants, turning them into monstrous creatures.
* "The Faculty" (1998) - While not worms, alien parasites infect the students and staff of a high school, taking control of their bodies and causing them to act violently.
Do any of these movies sound familiar? If not, please provide more details about the film you're thinking of (e.g., year released, any specific scenes you remember) and I'll do my best to help!