Police responding to a recent report of shots fired on Reservoir Street were able to arrest three subjects, while a police dog found a stolen pistol the men attempted to bury in a snowbank. The canine, named Ivan, inadvertently fired the gun while pawing through the snow, sending a bullet into a home at 82 Crescent St. Residents there were unharmed, as was the dog. An officer cleared the weapon to make sure it was safe; it was later determined the pistol had been stolen in Manchester, N.H., in October. Arrested were Jose Calderon, 28, Alexander Gonzalez, 21, and Jorge Henriquez, 26, all of Lawrence; Calderon allegedly told police he fired the gun because he was testing it.