Olean Police were called to Olean General Hospital for a man allegedly assaulting the hospital security guard. Police said when they arrived, Robert L. Nelson, 46, of Butternut Brook Road in Portville allegedly pulled a knife and threatened to stab the responding officers. Police said Nelson then fought with officers but was eventually taken into custody. Nelson was charged with menacing, disorderly conduct, assault, resisting arrest and criminal mischief. Court action is pending.