Swimmer Michael Phelps arrested for DUI

Law enforcement sources tell TMZ Sports, Michael Phelps was arrested for driving under the influence in Maryland last night.

The details of the arrest are not known yet but cops are preparing a statement and are expected to address the media soon. It's Michael's second driving under the influence arrest - he was popped in Maryland in 2004 when he was 19 years old. He struck a plea deal with prosecutors and plead guilty in exchange for 18 months probation.