From WENN.com

The Mean Girls star attended Justin Bieber's gig at Madison Square Garden and went on to the city's Club Avenue, where she was reportedly involved in an altercation with a female party-goer.

Police officers were called to the scene and took Lohan into custody, according to WABC-TV's Eyewitness News.

The actress was reportedly booked on an assault charge and remained at the police station as WENN went to press.