HALTON HILLS, Ont. -- Four women have been arrested in a police crackdown on shoplifting at a Toronto-area mall.

Halton regional police say they joined loss prevention experts from Mexx, Banana Republic and The Gap stores to respond to "increased criminal activity" at the Toronto Premium Outlets mall in Halton Hills.

A two-day operation was launched this week at the mall west of Toronto as a way of dealing with what police allege are "gangs of roving shoplifters" who have been plaguing many area malls.

Police say the arrests were made after officers changed into street clothes and began patrolling various stores.

Two Brampton women -- Qiana Gillespie, 32, and Dawn Williams, 46 -- are charged with theft under $5,000 and possession of stolen property, while Tamesha Nicola Duncan, 35, of Stayner, is charged with theft under $5,000.

Police say a 43-year-old woman who was also arrested had an outstanding immigration warrant and she has been released unconditionally to immigration officers.