Realm of the Rat King (2013)

from the Introduction:
When the rats swarmed out of the woods and through the village of Roarke, nobody paid much attention. But when they swarmed through Trent and Yarah only a few days later, the locals knew something foul was afoot.

Survivors describe the event as though a wave of rats crested at one end of the village and rolled all the way to the other. Along their chosen path they would enter every building by door, window, or chimney, seeking any small shiny object or food they could easily carry away.

The villagers were largely unharmed if they simply got out of the way, but a few stopped to fight back and paid the price. Other local villages have asked for help, but in the meantime have started a network of lookouts to give the people even a little warning to flee for their lives.