ROCK ISLAND, Ill. (WLS) -- A man attacked a woman at library in Rock Island, Ill., but a quick-thinking witness came to her aid."I look and I see a man grabbing a woman and her face was so fearful," Nikki Clark said.Clark heard the woman's cries and saw the man grabbing her from behind. Clark is disabled and wasn't able to help to do anything physically to help the woman, so she snapped the man's picture and screamed for help.He was arrested a short time later. Clark hopes her story will encourage to step in and help others who are in danger.