Reno police found the 12- and 13-year-old girls at the Kietzke Lane Walmart at around midnight on Tuesday.
"They called us because they were cold and hungry," Reno Police Department Sgt. Chris Lang said.
The girls are being held at the Jan Evans Juvenile Detention Center as runaways and to check on their welfare, police said.
Meanwhile, Reno police arrested Blake Holmes, 18, of Ridgecrest, Calif., on four counts of sexual assault on a minor younger than 14 three counts of lewdness with a minor. His bail was set at $110,000.
Police said he formed a relationship with the girls over the Internet and then brought them to the Reno area in a stolen vehicle.