Illinois police are searching for a college student who disappeared after leaving a Chicago nightclub Sunday.

Katie O'Connell, 20, was last seen getting into a cab outside of the bar Underground, at 56 W. Illinois, where she had been with her friends, said her father Bernie O'Connell.

Katie is 5' 10'', 135 pounds, with long brown hair and blue eyes. Her father told Fox News that she was last seen wearing a white blouse, black skirt and burgundy pea coat.

Her father said he had spent the earlier part of the day with Katie, helping her get ready for the birthday party she was going to at the nightclub.

"She was very happy. We spent the day getting ready for the party," he said.

He said they went shopping for clothes and she went tanning on the day she disappeared.

Police are interviewing her friends who she was last seen with at the club. Her friends said Katie had told them she was tired and was going to take a cab home, Bernie O'Connell told Fox News.

Anyone who might have information about Katie's whereabouts is asked to contact the Oak Brook Police Department at 630-368-8744.