Authorities in the South Bay have arrested a woman and a girl suspected of posing as potential clients at San Jose fitness clubs in order to steal wallets, car keys and vehicles, a Santa Clara County sheriff’s spokesman said today.Sheriff’s deputies stopped a Ford F-150 truck in unincorporated San Jose around 1 a.m. Saturday after determining that the vehicle was stolen. The car contained six people, including a 16-year-old girl behind the wheel who was on probation for attempted robbery, sheriff’s spokesman Sgt. Rick Sung said.Deputies searched the car and found the driver and another passenger, an 18-year-old woman, to be in possession of a variety of driver’s licenses, credit cards, wallets and money believed to be stolen from two San Jose fitness centers, Sung said. Sheriff’s investigators believe the woman, Shantinee Martinez, and the girl, whose name has been withheld due to her age, visited a 24 Hour Fitness and a Bally Total Fitness in San Jose last week and posed as prospective customers.The pair would ask to tour the facility or use the restroom in order to gain access to the women’s locker room, Sung said. Once inside, they would allegedly search for unsecured lockers and steal car keys and wallets, he said. Using the car keys, Sung said, Martinez and the juvenile allegedly stole several vehicles out of the gyms’ parking lots. The truck that deputies pulled over was reported stolen from the 24 Hour Fitness at 375 N. Capitol Ave. in San Jose.Sheriff’s detectives say they found additional wallets that did not belong to patrons at either health club, leading them to believe the pair robbed other fitness centers as well. Anyone with information on similar crimes should call Detective Sgt. Elder at (408) 808-4500, or use the anonymous tip line at (408) 808-4431.The 16-year-old girl was booked into juvenile hall for possession of a stolen vehicle, stolen property and a parole violation. Martinez is also being held for possession of stolen property, although the lead detective on the case said that the pair will likely face additional burglary and conspiracy charges once the investigation is completed.Three other passengers in the truck, all between 16 and 18 years old, were cited for underage possession of alcohol. The sixth passenger, a 16-year-old girl reported missing in San Jose, was returned home, Sung said.