Silence upon the hill

When a simple and fun field trip to a town, that was told to have deadly gasses and finally was deemed safe due to the 'gases being less harmful and almost completely gone.' Soon became an fight for lives when an incident with the bus happens, and they wake up in a town full of fog and falling ash and snow. That was filled with roaming monsters and creatures of all kinds. Will they find their way out of the town, and find out why they were in this town instead of the one intended. And why was the sign saying 'welcome to silent hill'?