RCMP Const. Krista Vrolyk said the boy was with other youth and a parent in Spirit Square in the downtown core of Quesnel, 672 kilometres north of Vancouver, when the incident occurred just before 10 p.m. Thursday.
The woman tried to shake the boy's hand, but grabbed him by the wrist and pull him towards a nearby pickup truck, said Vrolyk.
That's when the teenaged girl, the boy's 13-year-old friend, took action.
"It just so happened that the 13-year-old was a little bit closer and kind of quick to act," said Vrolyk.
She said the girl, who is of slight stature and thin, physically pulled the boy away from the woman.
"Her concern for her little buddy is what motivated her to step in and take action," said Vrolyk.
The senior fled and was quickly tracked down by Mounties who arrested her for attempted kidnapping, she added.
Neil MacKenzie, a spokesman for British Columbia's criminal justice branch, said Katharina Abrams has been charged with forcibly seizing another person, remains in police custody and will appear in court again on Sept. 18.
Vrolyk said RCMP in Alberta and B.C. have dealt with the accused in the past, but not over any similar incidents.
"This seems to be an isolated incident with this female," she said, adding that police are investigating her motive.
Darryl Plecas, a professor of criminology at the University of the Fraser Valley, said incidents of attempted abductions between woman in their senior years and young children are rare.
"I'm tempted to say it's so rare it doesn't register," said Plecas.
He said there are more than 2-million crimes committed across the country annually, and researchers could probably count on one hand the number of similar cases.
Vrolyk said police are looking at formally recognizing the girl for her bravery.
"We're all pretty impressed with her actions from (Thursday). There's no doubt about that," she said, adding that everybody is relieved with how things worked out.
"The thoughts of what could have happened are the worst part of it all."
-- by Keven Drews in Vancouver