GILBERT, Ariz. -- Gilbert police arrested a man on Wednesday on allegations he took pictures up a 13-year-old girl's skirt at an east Valley Wal-Mart store.

Bradley Allen Trotter was taken into custody without incident after officers called to the scene conducted a traffic stop in another area of the shopping center's parking lot, police said.

Police said the girl's mother followed Trotter out of the store at 2501 S. Market St. and notified police and store security.

Gilbert police said they are concerned that there may be additional victims in this case.

Police said they are aware that Trotter had recently been at the following locations:

Wal-Mart at 4505 E. McKellips in Mesa
July 23 at 11:00 a.m.

Wal-Mart in Tolleson
July 22 at 10:45 a.m.

Target in Tolleson
July 22 at 11:38 a.m.

Police said people who witnessed -any incidents involving Trotter are asked to contact the Gilbert Police Department at 480-503-6500.