A MEETING OF the North Hills Squirrel Reduction Task Force at Pine Township Park was interrupted when several participants were hit with spherical projectiles. Although there were no serious injuries, the meeting was hurriedly adjourned and the park evacuated. Police later determined the projectiles to be black walnuts from a nearby tree. As yet neither a suspect nor a motive has been determined in the attacks. A reward is offered for information leading to the arrest and conviction of the unknown assailant.