For many years now, visitors to Svalbard, the Norwegian chain of islands within the Arctic Circle, have been told when they arrive to the islands, “If you move outside of the center of Longyearbyen, you must have a loaded rifle and someone who knows how to use it.”

But even a perimeter alarm system and firearms were not enough to save a British teenager who was mauled to death on a remote Norwegian island in the Arctic Circle on August 5.

Horatio Chapple, 17, was killed and four other expedition members were injured by a polar bear that came into their tent.

The bear was shot and killed by one of the leaders of the group, which was taking part in a five-week Arctic expedition.

The injured campers were airlifted to a hospital 25 miles away in Longyearbyen, after the group used a satellite phone to call for help at 7:30 a.m. Friday morning.

The British Schools’ Exploring Society, a youth development charity based at the Royal Geographical Society in London, said that the injured included two trip leaders–Michael Reid, 29, and Andrew Ruck, 27–and two teenagers, Patrick Flinders, 16, and Scott Smith, 17.

The expedition had taken all the right precautionary measures, but a warning tripwire system around the camp had failed to activate. The tripwire is commonly used around the Arctic to scare off polar bears, which bump into the wire triggering a flare that creates light and noise to either frighten the predator away or at least alert campers to its presence.