German authorities announced Wednesday they would carry out their own inquiry into a freak accident in the Austrian Alps that killed nine German skiers on Monday. A helicopter flying above the ski resort of Sölden, some 60 kilometers (35 miles) from Innsbruck, dropped a container full of concrete directly onto a cable car carrying summer skiers on Monday. The impact sent the cable car crashing into the mountain, killing three people, while another six skiers were shaken out of the car ahead of it, sending them plunging down the mountain to their deaths. A German ski instructor who witnessed the accident, Marcel Knoch, said on Wednesday that the helicopter had flown dangerously close to the cable car several times. The Munich state prosecutor's office will investigate charges of manslaughter and causing bodily harm through negligence, chief prosecutor Rüdiger Hödl said. Six of the victims were children aged 11 to 13, and all came from the Black Forest region in southwestern Germany.