GRAND CANYON NATIONAL PARK • Attention, Grand Canyon visitors - watch your step before attempting a selfie from the edge of the vertiginously deep and perilously steep American landmark.
The park surrounding the enormous canyon - the second-most visited US national park, after the Great Smoky Mountains - has experienced a surge in fatal accidents, with at least four visitors dying in as many weeks in March and April.
The views that draw millions to the park in the high Arizona desert are stunning - both in their rich earth hues and in the sheer immensity of the gap cleaved over eons by the unceasing Colorado River as it winds through the canyon bottom.
But the views can also distract or disorient visitors - some of whom take risks despite park rangers' constant warnings - and the result can be fatal.
The body of a Japanese tourist was the first one found this spring, in a wooded area some distance from the rocky cliffs.
Then came three fatal falls, including that of a 50-something tourist from Hong Kong who toppled over the edge while snapping photos.
The park has placed protective barriers at some popular vista points, but "we don't want to put barriers everywhere", park spokesman Kris Fister said.
But of the dozen people who, on average, die each year in the canyon, relatively few fall to their deaths, according to park service statistics.
Most deaths are linked to the dramatic change in altitude and to dehydration in the crushing summer heat faced by hikers - despite the frequent warning signs that offer advice like: "Don't become a statistic" and "Down is optional, up is mandatory."