Lethbridge Regional Police allege three women confined an 18-year-old woman and assaulted her for several hours.
The woman was taken to hospital with extensive but non-life-threatening injuries.
Police say their investigation uncovered that the victim had accompanied a female acquaintance for a drive and was taken to a farm outside the city.
A short time later two other female acquaintances arrived and the three women began assaulting the 18-year-old, according to police.
The victim was driven back to the city after being assaulted. Two women are currently in custody.
"This was not a random incident," said police in a release.
The three women — a 19-year-old from Coalhurst, a 24-year-old from Coalhurst and a 22-year-old from Lethbridge — are facing charges for assault, kidnapping, robbery and unlawful confinement.