A familiar horror reached Pooja Kanda first on social media: There had been a sword attack in London. And then Kanda, who was home alone at the time, saw a detail she dreaded and knew all too well.

A man with a sword had killed a 14-year-old boy who was walking to school. Two years ago, her 16-year-old son, Ronan, was killed by two sword-wielding schoolmates while walking to a neighbor’s to borrow a PlayStation controller.

“It took me back,” Kanda, who lives near Birmingham, said about Daniel Anjorin’s April 30 killing in an attack in London’s Hainault district that also wounded four people. “It’s painful to see that this has happened all over again.”

In parts of the world that ban or strictly regulate gun ownership, including Britain and much of the rest of Europe, knives and other types of blades are often the weapons of choice used in crimes. Many end up in the hands of children, as they can be cheap and easy to get.