Four American Marines died on Friday after their plane crashed during a training exercise in Norway, the country’s prime minister announced on Twitter. “It is with great sadness we have [received] the message,” prime minister Jonas Gahr Støre wrote. He said the Marines had been participating in a NATO exercise called “Cold Response,” in which soldiers from more than two dozen countries are conducting drills in cold weather conditions. A statement provided by the Marine Corps to CNN confirmed that four Marines had been “involved in an accident” in a MV-22B Osprey, but the statement did not provide details on their identities or specify whether they had been killed.