Investigators scoured on Monday the heavy snow enveloped scene of a passenger plane crash near Moscow that has left all 71 people on board dead. Snow at the site of the crash was waist-high in places, making it difficult to access, with emergency workers forced to reach the wreckage by foot and use snowmobiles. Russias Investigative Committee said it would consider explanations for the crash including human error, technical failure and weather conditions, as the country has experienced record snowfall in recent weeks. Around one hundred investigators and criminologists were working at the scene of the Antonov An-148 crash, the Committee, which investigates major incidents, said. The emergency services ministry said at least one of the two black boxes had been found.  The plane went down in the Ramensky district around 70 kilometers southeast of Moscow after taking off from Domodedovo airport in the Russian capital and disappearing off the radar at 2:28 pm Sunday. "Sixty-five passengers and six crew members were on board, and all of them died," Russias office of transport investigations said in a statement. A Swiss citizen and a citizen of Azerbaijan were among the fatalities on a list released by the emergency services ministry. Three children also died including a five-year-old girl. The flight was operated by the domestic Saratov Airlines and was headed for Orsk, a city in the Ural mountains.