Updated

Six Russians were killed and two seriously injured when the snowmobile and sled they were riding veered off an Italian Alpine ski slope at night, slammed into a barrier and flew through the air into a ravine.

The accident occurred Friday night and when rescuers arrived at the scene six of the victims were found dead on the slope of Mount Cermis, in the Trentino-Alto Adige region of northeast Italy, said Cavalese Fire Department Cmdr. Roberto Marchi.

"It is clear that the fundamental cause is recklessness and imprudence," Marchi told Sky TG24 TV in an interview on the slope Saturday. It is labeled "pista nera" or black ski run, indicating a level of steepness and other difficult conditions suitable only for the most experienced skiers.

Six of the people involved in the accident were Russian tourists and the other two were Russians who worked in Italy in the tourist industry.

Cavalese Mayor Silvano Welponer said that putting a driver and passenger in the snowmobile and having it pull six passengers in the sled "made for a very heavy load. You have to know what you are doing and have the experience" to safely handle that, he said.

The ANSA news agency said authorities were performing tests to determine if the snowmobile's driver -- who survived the crash -- was drunk.

The sled-towing snowmobile cut a spectacular trajectory after it veered off the slope on a curve, hit the manmade barrier, flew through the air while shearing the tips off tree branches, then landed in the ravine, Italian news reports said.

RAI state radio said the slope was unlit, and other Italian news reports quoted local officials as saying it had been closed for the day and that the only vehicles allowed on it when it is open are staff or rescue ones. The Russians were believed to have dined at the top of the slopes and were heading back to their hotel when they crashed, the reports said.

The Russian consul general in Milan, Alexei Parmonov, said on Russian state television that he was in contact with Italian investigators, who he said suspect the crash was caused by excessive speed. They also were checking the possibility of a mechanical malfunction.

Italian prosecutors formally opened a probe to see if manslaughter charges should be filed, Italian news reports said.

Parmonov identified the four men and two women who died in the crash. Five of them and also one of the injured men were tourists from Krasnodar, a region in southern Russia that includes Sochi, which is preparing to hold the 2014 Winter Olympics. One of the dead women and the other injured man worked in Italy in the tourist industry.

The Russian diplomat identified the dead as Denis Kravchenko, Irina Kravchenko, Vyacheslav Sleptsov, Yulia Yudina, Lyudmila Yudina and Rafilya Pshenichnaya. The injured, he said, were Boris Yudin and Azat Agafarov. All except Pshenichnaya and Agafarov were tourists from Krasnodar. Yudin's 17-year-old son, who stayed behind in the hotel, lost his mother and sister in the accident, while his father was hospitalized with multiple fractures, Parmonov said.

A day of entertainment had been planned for the Val di Fiemme ski resort area Saturday, ahead of World Cup cross-country ski competition, but the festivities were canceled because of the accident.

Mount Cermis suffered two deadly accidents in the past.

In 1998, a U.S. Marine jet, flying low on a training run from a nearby air base, accidently sliced a ski gondola's cable, sending the cable car crashing to the ground and claiming 20 lives. The accident triggered months of tensions between Italy and the United States, two traditional good allies.

In 1976, a ski gondola broke off from its cable and plunged to the slope, killing 42 persons.