SAN MARCOS–A solo vehicle collision Sunday morning left a driver unconscious behind the wheel, traffic authorities say.

The man crashed head-on into a tree on South Twin Oaks Valley Road, north of the intersection of Village Drive, in San Marcos, according to Sheriff’s deputies.

Deputies and San Marcos firefighters found the man unconscious behind the wheel of the vehicle. Once extricated from the vehicle, the man was transported by paramedics to Palomar Medical Center for serious, but non-life threatening, injuries to his head, chest and abdomen. The driver’s identity has been withheld pending the notification of his relatives or next of kin.

Prior to the collision, witnesses observed the Hispanic male adult driver in a red 2008 Nissan Versa swerving between lanes just prior to colliding with the tree.

Alcohol and/or drug impairment has not been ruled out as a factor in the collision.

The investigation and cause of the collision is on-going.