MINNEAPOLIS (WCCO) — An investigation is underway after a woman died over the weekend while in custody in a western Wisconsin jail.

The St. Croix County Sheriff’s Office says deputies found 46-year-old Danyiel Mager, of New Richmond, lying in her bunk late Sunday morning, not breathing. She had been in the jail since early Saturday, when she was arrested on outstanding warrants.

After an ambulance arrived at the St. Croix County Jail, deputies and medics attempted to resuscitate Mager, but were not successful.

Mager’s cause and manner of death will be determined by the Ramsey County Medical Examiner’s Office in St. Paul. St. Croix County, Wisconsin, is located just east of the Twin Cities, across the Mississippi River.

The sheriff’s office says it’s investigating the death, noting that Mager didn’t appear to suffer any external or internal injuries.