The collapse Sunday afternoon sent ice, snow and rocks pelting hikers on a popular Marmolada Peak trail, killing at least six and injuring eight, authorities said. Italy’s National Alpine and Cave Rescue Corps tweeted that the ongoing search at the summit included at least five helicopters and rescue dogs. He said the hikers were “struck by the detachment of the serac,” using a term for the top of a glacier. “There are eight injured, two of them in serious condition.” The dispatch service SUEM (Servizio Urgenza Emergenza Medica), based in the nearby Veneto region, said 18 people who were above the area where the ice hit would be evacuated by the rescue corps. The dispatch service said the avalanche consisted of a “pour of snow, ice and rock.” Marmolada, which is about 3,300 meters (11,000 ft) high, is the highest peak in the eastern Dolomites. “A rockfall caused a crevasse to open in the glacier, leaving approximately 15 people trapped,” emergency officials said on Twitter. The Alpine Rescue Service said in a tweet that the section was interrupted near Punta Rocca (Rock Point), “along the route normally used to reach the summit”. It was not immediately clear what caused the section of ice to split. Walter Milan, a spokesman for the Alpine rescue service, told Italian state broadcaster RAI that an intense heatwave that has gripped Italy since late June may be a factor. “The heat is unusual,” Milan said, noting that temperatures in recent days at the summit had exceeded 10 C (50 F). “That’s too much heat” for the top, Milan said. “It’s clearly something abnormal.” The injured were airlifted to several hospitals in the Trentino-Alto Adige and Veneto regions, according to rescue services.