By David Ljunggren

OTTAWA (Reuters) - A Canadian nurse was charged on Tuesday with using drugs to murder eight elderly patients in long-term care facilities in an alleged killing spree that ran for seven years.

Elizabeth Wettlaufer, 49, is accused of killing five women and three men in the Ontario towns of Woodstock and London between 2007 and 2014. The dead ranged in age from 75 to 96.

"The victims were administered a drug," Woodstock Police Chief William Renton told a televised news conference, declining to give further details. Wettlaufer appeared in court on Tuesday and was remanded in custody.

The criminal case is the largest in Ontario since 2006, when five men were charged with murdering eight biker gang members. They were convicted and sentenced to life in prison.

Renton said officers began probing the deaths in September after receiving a tip.

"We are confident at this time that all of the victims have been identified," he said.

The Canadian Association of Retired Persons said it was shocked by the tragic nature of the alleged crime. Mass killings are uncommon in Canada.

"For nurses and staff to be part of a violence problem, we think this is rare... it is extraordinary, and thankfully so," spokesman Anthony Quinn said from Toronto.

In 1997 a Canadian doctor was charged with murdering a terminally ill cancer patient. A judge later threw out the case.

Seven of the dead lived in a Woodstock facility run by Caressant Care. The firm said Wettlaufer had left her job in 2014.

Doris Grinspun, head of the Registered Nurses' Association of Ontario, said she was devastated.

"An event like this is most, most, most unusual, the first actually in all my 20 years at the association... these things are horrifying to all of us. They are the exception, the very rare exception," she told the Canadian Broadcasting Corp.

People residing in the same apartment building as Wettlaufer described her as a pleasant person who lived alone with her dog.

"We would chat and have laughs. She seemed like an everyday, normal kind of person," Derek Gilbert told CBC.

A LinkedIn profile in the name of Elizabeth Wettlaufer said she was a nurse who worked at the Woodstock home from June 2007 to March 2014. "Administering medications" was listed as one of her responsibilities.

In March, Italian police arrested a 55-year-old nurse on suspicion of murdering 13 elderly patients in the intensive care ward where she had worked for decades.

(Reporting by David Ljunggren; Editing by David Gregorio and Dan Grebler)