British police found the elderly woman, identified as Palmira Silva, in Edmonton around 1:00 p.m. local time.
Detective Chief Inspector John Sandlin acknowledged the nature of the murder could raise concerns that it was a terrorist act but downplayed that possibility.
"Whilst it is too early to speculate on what the motive behind this attack was I am confident, based on the information currently available to, that it was not terrorist related."
Police arrested an unidentified 25-year-old man on suspicion of Silva's murder after responding to calls about a knife-wielding man in the neighborhood whom eyewitnesses believed had attacked an animal in a back garden.
Police Commander Simon Letchford described the efforts required to capture the armed suspect. "Officers had to do everything they could to make other people safe and evacuate houses and put their lives on the line to make sure this individual did not cause further harm."
Ultimately, officers cornered the armed man and used a Taser to immobilize him. The suspect was hospitalized after his arrest.
It is unclear whether Silva knew her assailant.
Scotland Yard's Homicide Command is investigating.