Mel Gibson film involving a bomb?

has mel gibson who is in army an try to stop a bomb, this bloke who carries it takes a pill and he is dying i think, and snipers follow him around town, as his family died, but he is having second thoughts and goes in a church, shoots himself and they difuse the bomb. then another is on a truck that is followed. at the begining there is a giant explosion on a train and a farmer and his wife are destroyed???? what is it please. thanks.