A nurse in Ontario was arrested and charged with murdering eight patients, Canadian authorities said Tuesday. The alleged killings took place at two elderly care facilities between 2007 and 2014, where the suspect, Elizabeth Wettlaufer, was employed.

The eight patients were both men and women between the ages of 75 and 96 and "were administered a drug," said Ontario Provincial Police detective superintendent Dave Truax in a press conference.

"We're not in a position at this time to comment further on the specifics of the drug as it forms part of the evidence that is now before the courts," he said, adding, "All I can offer is there are obviously a number of drugs that are stored and available in long-term care facilities."

Wettlaufer was registered as a nurse in 1995 and remained active until she resigned on September 30 of this year, the day after the police launched an investigation into her activities on duty.

William Renton, the chief of police in Woodstock, Ontario, where some of the alleged killings took place, said, "We are confident at this time that all of the victims have been identified."

The Registered Nurses' Association of Ontario issued a statement calling the killings "horrifying," but stressing that such crimes are extremely rare.

People who lived in Wettlaufer's apartment complex described her as a pleasant person who resided there alone with her dog. She was active on social media, often posting about recipes and religion.

Authorities have yet to commit on what could have motivated Wettlaufer to target her patients. 

es/gsw (AFP, Reuters)