  We present the results of a photon cluster search in the gamma-ray sky
observed by the Fermi Large Area Telescope, using the new Pass 8 dataset, at
energies higher than 10 GeV. By means of the Minimum Spanning Tree (MST)
algorithm, we found 25 clusters associated with catalogued blazars not
previously known as gamma-ray emitters. The properties of these sources are
discussed.
