EDMONTON -- Police have confirmed that a fire that broke out at the women's prison in west Edmonton overnight was deliberately set.

According to a police spokesperson, a disagreement broke out between staff and inmates on Thursday night. A police negotiator was brought in to speak with the inmates, but some articles in a cell were lit on fire.

Staff at the institution evacuated the inmates.

Crews were called to the prison at 11:27 p.m. The fire was reportedly under control by 1 a.m.

Five women were treated on scene for smoke inhalation, Edmonton Fire Rescue Services told CTV News Edmonton.

Alberta Health Services said two women were taken to hospital in stable condition, but Edmonton police tell CTV News Edmonton that three staff and three inmates were taken to hospital.

The arson and the events leading up to it are under investigation.