UPDATE: Cops tell TMZ alcohol was NOT a factor in the crash. We're told cops interviewed Phelps after the accident and determined that a field sobriety test was not necessary.
We're told Michael refused medical treatment and left in a "personal vehicle."
Michael Phelps was just involved in a three-car accident in his hometown of Baltimore.
Phelps reportedly emerged from the wreck unscathed, but a woman in the other car was shaken up and taken to a local hospital. We're told she complained of "head and arm pain."
The accident occurred around 9pm local time.
A police spokesman says the Olympic Gold Medal winner was driving a Cadillac Escalade, which collided with a Honda accord.
We're told by witnesses on the scene -- the two cars collided after someone ran a stoplight -- and then hit a third car that was not moving at the time.
Police are investigating the cause of the crash.
One of the local papers is reporting that a passenger in Phelps' car was also injured, but it's unclear as to the extent of that person's injuries.
We're told there is already a tow-truck on scene removing Phelps' ride. We're told Michael's car received "heavy damage."