It is shown that the correlations predicted by relativistic quantum field theory in locally normal states between projections in local von Neumann algebras $\mathcal{A}(V_1),\mathcal{A}(V_2)$ associated with spacelike separated spacetime regions $V_1,V_2$ have a (Reichenbachian) common cause located in the union of the backward light cones of $V_1$ and $V_2$. Further comments on causality and independence in quantum field theory are made.