From Lancaster County,PA wiki--

The outbreak of Pontiac's War in the summer of 1763, coupled with the ineffective policies of the provincial government, aroused widespread settler suspicion and hatred against all Indians in the frontier counties, without distinguishing among hostile and friendly peoples. On December 14, 1763, the Paxton Boys, led by Matthew Smith and Capt. Lazarus Stewart, attacked Conestoga, killing the six Indians present, and burning all the houses. Officials sheltered the tribe's fourteen survivors in protective custody in the county jail, but the Paxton Boys returned on December 27, broke into the jail, and massacred the remaining natives. The lack of effective government control and widespread sympathy in the frontier counties for the murderers meant they were never discovered or brought to justice.[18]