In a large bowl, combine 2 cups flour, sugar, yeast, and salt. Add warm water and beat until smooth. Stir in enough remaining flour to form a soft dough.
Turn onto a floured surface; knead until smooth and elastic, about 6-8 minutes. Place in a greased bowl, turning once to grease the top. Cover and let rise in a warm place until doubled, about 1 hour.
Punch dough down. Turn onto a lightly floured surface; divide in half. Shape each into a loaf. Place seam side down on greased baking sheets. Cover and let rise until doubled, about 30 minutes.
Preheat oven to 375°F (190°C). With a sharp knife, make four shallow slashes across the top of each loaf. Bake for 25-30 minutes or until golden brown. Remove from pans to wire racks to cool.