Thunder Bay police dealt with a potentially serious situation this morning. Officers were called to a disturbance on the North side just after 3:30 this morning and when they arrived found the door open and could hear some noise. Once inside they discovered a man armed with a knife standing over a woman. Police subdued the man and arrested him. About an hour later a man was assaulted on North May street by his brother in law. The victim was sent to the hospital after suffering a broken shoulder and a 20 year old man was arrested and charged with assault.