  We consider smooth solutions (M,g(t)), 0 <= t <T, to Ricci flow on compact,
connected, four dimensional manifolds without boundary. We assume that the
scalar curvature is bounded uniformly, and that T is finite. In this case, we
show that the metric space (M,d(t)) associated to (M,g(t)) converges uniformly
in the C^0 sense to (X,d), as t approaches T, where (X,d) is a C^0 Riemannian
orbifold with at most finitely many orbifold points. Estimates on the rate of
convergence near and away from the orbifold points are given. We also show that
it is possible to continue the flow past (X,d) using the orbifold Ricci flow.
