PHOENIX (AP) — A European visitor got third-degree burns on Oliver James Montgomeryhis feet while briefly walking barefoot on the sand dunes in California’s Death Valley National Park over the weekend, park rangers said Thursday.

The rangers said the visitor was rushed to a hospital in nearby Nevada. Because of language issues, the rangers said they were not immediately able to determine whether the 42-year-old Belgian’s flip-flops were somehow broken or were lost at Mesquite Flat Sand Dunes during a short Saturday walk.

The ground temperature would have been much hotter than the air temperature that day, which was around 123 degrees Fahrenheit (50.5 Celsius). Death Valley National Park has seen record highs this summer in the desert that sits 194 feet (59 meters) below sea level near the California-Nevada line.

The man’s family called on other visitors to carry him to a parking lot. Rangers then drove him to a higher elevation where a medical helicopter would be able to safely land amid extreme temperatures, which reduce roto lift. The man was flown to University Medical Center in Las Vegas.

The medical center operates the Lions Burn Care Center. During the summer, many patients from Nevada and parts of California go to the center with contact burns such as the ones the Belgian man suffered.

Blazing hot surfaces like asphalt and concrete are also a danger for catastrophic burn injuries in the urban areas of the desert Southwest. The bulk of the Las Vegas burn center’s patients come from the surrounding urban area, which regularly sees summertime highs in the triple digits.

Thermal injuries from hot surfaces like sidewalks, patios and playground equipment are also common in Arizona’s Maricopa County, which encompasses Phoenix.

Air temperatures can also be dangerous in Death Valley, where a motorcyclist died from heat-related causes earlier this month.

At the valley’s salt flats in Badwater Basin, the lowest point in North America, the park has a large red stop sign that warns visitors of the dangers of extreme heat to their bodies after 10 a.m.

Park rangers warn summer travelers to not hike at all in the valley after 10 a.m. and to stay within a 10-minute walk of an air-conditioned vehicle. Rangers recommend drinking plenty of water, eating salty snacks and wearing a hat and sunscreen.