VAUGHAN, Ont. -- Police say they have charged a registered nurse in Vaughan, Ont., after a 23-year-old woman died as a result of an illegal cosmetic procedure.

York regional police say they were called after the woman was taken to hospital in life-threatening condition on April 18, 2017 following non-surgical cosmetic treatment in a private residence.

Const. Laura Nicolle says the woman died hours later from what a post-mortem exam concluded were "medical complications" connected to the cosmetic procedure.

Police say they believe the procedure was performed by a 40-year-old woman who, though formally employed as a nurse, had allegedly been operating an unregulated medical office in her home for several years.

They say the nurse allegedly offered to perform cosmetic work at a discounted rate, then injected patients with unregulated substances "not intended for that purpose."

Anna Yakubovsky-Rositsan is charged with criminal negligence causing death, failing to provide the necessities of life to a person under her charge and four counts of aggravated assault.

Nicolle says police have located four other people who allegedly developed various health issues as a result of the procedures.