Ontario's health ministry is investigating after an 87-year-old woman spent more than 24 hours trapped in an elevator at a long-term care home in Mississauga until she was finally freed early Christmas morning.

The region of Peel is also looking into the ordeal, which began after Rosalie Rowsell went out with her family the Sunday before Christmas and was dropped off at the front doors of the facility that night.

"The Ministry of Health and Long-Term Care takes very seriously any adverse incidents involving a resident of a long-term care home," said ministry spokesman David Jensen.

"The ministry’s Hamilton service area office has begun an inspection of Malton Village Long-Term Care Centre and will be completing a report detailing the outcome of the inspection."

Staff at the facility believed Rowsell was staying with her family and didn't determine until Christmas Eve she was missing, Peel Region chair Emil Kolb said in a statement.

They called the family who told them the woman had returned to the facility the night before. After staff failed to find her during a search, Peel regional police were called, he said.

Police conducted a room to room search of the facility and after about two-and-a-half hours, at about 2:01 a.m. Christmas morning, Rowsell was found inside a malfunctioning elevator that had been taken out of service on the morning of Dec. 24, said Peel region Const. Thomas Ruttan.

Firefighters were called to pry open the doors and free the woman, he said.

"We believe she became trapped in the elevator between floors on her way to her room and was unable to obtain assistance for the next 24-hours," said Kolb.

"This is one of the key areas of focus in our investigations: How could that happen?"

The woman was treated by paramedics for dehydration at the scene and taken to hospital for evaluation. She returned to the centre on Christmas Day and is being kept under observation.

The Technical Standards and Safety Authority is examining the elevator but police say there is no criminal aspect to the case since Rowsell entered the elevator of her own fruition.

The region of Peel has apologized to the woman and her family "for this gap in our duty," said Kolb.

Corrective measures are being taken including ensuring residents and their families sign in and out of the centre and staff are reviewing the centre's leave of absence policy, he said.

Malton Village which has 160 beds opened in 2004.