OLYMPIA, Wash. -

Washington State Patrol detectives have arrested 21 people as part of an online sex predator sting.
   
Sgt. Carlos Rodriguez tells The Olympian that operation resulted in four children being rescued from abusive situations. He says the suspects have a range of ages and backgrounds and the majority of them have no prior criminal history.
   
The patrol's Missing and Exploited Children Task Force worked with local law enforcement to conduct the undercover operation on Sept. 7-18.
   
Several of the arrests were made at a Tumwater apartment building. Detectives say they posed as a mother offering her underage children for sex in an online advertisement. The suspects were charged with attempted rape of a child because they arrived at the location after arranging to have sex with a minor.