Three Americans were killed on Friday when their private jet broke up and burst into flames on landing at an airport in the south of France, officials said. Emergency services battled to put out the blazing twin-engined Gulfstream IV at Castellet airport, between the Mediterranean cities of Marseille and Toulon. The dead are two men aged 24 and 60 and a woman aged 30, local police said, adding that all were American. The plane crashed on landing at the private airport at Castellet after flying from Nice, an air safety official said. \"The plane broke in two, one bit ended up in the lake at the end of the runway and the other bit caught fire,\" another official told AFP, requesting anonymity. \"We saw a big grey plane that made a lot of noise before crashing,\" said Florent Picaud, who works near the airport. \"There was a big cloud of smoke and flames coming from the plane. The emergency services arrived very quickly, it was impressive,\" he said.