Naked Washington man crashed his car into a tree while having sex with a woman while her newborn baby was on the backseat (Details, pics)

A man is behind bars and a woman in the hospital after the car they were driving in went off the road and hit a tree of Wednesday - allegedly while they were having sex.

Washington State Patrol arrived at the scene shortly after 6pm and found the couple - Michael G Tonkin and Daisy L Laroque - both fully naked with the woman's three-month-old child in the backseat.

Tonkin, who had three prior DUI arrests, was brought to the Pierce County Jail, according to WSP spokeswoman Brooke Bova, while Laroque was taken to the hospital with broken bones.

The newborn in the backseat was not injured in the crash. It was a bystander who gave a witness account to WSP officers who reported that the couple exited the car naked on Wednesday. Tonkin is now being held on a number of charges including DUI and child endangerment.

He is also likely to be charged with vehicular assault for the incident.

It is unknown if Laroque will face any charges.