In a bowl, combine flour, baking powder and salt. Cut in the shortening until crumbly. Stir in the buttermilk, just until moistened. Knead on a floured surface for 1 minute. Roll out to 1/2 inch thickness; cut with a 2 1/2 inch biscuit cutter. Place on a greased baking sheet. Bake at 450 degrees for 10-12 minutes or until golden brown.