Disaster movie with chemical tanker truck cannot figure out title?

I'm trying to find a movie i watched on Hulu a few years back. It had a secret service agent in it. This movie took place in a forest. The tanker truck some how went off the road and spilled chemicals into to a river. the forest is taken over by a group of people who start to quarantine the people in the forest. i cannot figure out the name of this movie any ideas?