Chad Ryan Desoto, 21, of Tamuning was taken into custody at the scene of the Tuesday night incident in the Tumon tourist district, the Guam Pacific Daily News reported.
Desoto is named on two counts of murder, 13 counts of attempted murder and 13 counts of aggravated assault, the newspaper said, adding further charges were possible.
Police had said earlier three people were dead and 11 injured in the attack near The Plaza and Outrigger Resort Guam.
The condition of the wounded wasn't known and the discrepancy in the casualty totals was not explained.
Ashley Quichocho, 18, of Dededo told the newspaper she saw the car crash into the front of a store before a man get out and ran toward bystanders he started stabbing with a knife.
"He started stabbing someone and I started freaking out. He was just running back and forth stabbing people," she said.