The Reaping (2007) on Netflix

The atheistic Katherine Winter is a former Catholic missionary that lost her faith on God after losing her daughter and her husband in Sudan, sacrificed by the locals that blamed them for the long drought. Presently she investigates religious phenomena with the intent of debunking them, finding a scientific cause for the event. She is invited to go to the small town of Haven, in Louisiana, where the river turned into blood after the death of a boy. After her arrival, each of one of the ten biblical plagues happens in the location dazing Katherine, who discloses the evil secret of the dwellers.