Powerful winds in northern China blew a roof off a building, causing damage to several vehicles.br br The dramatic footage, shot in the city of Baoding in Hebei Province on March 18, shows a metal roof being blown off a building and striking several vehicles moving on a road.br br According to reports, the local authority has issued a blue warning signal (the lightest warning signal) for the wind on March 17. br br Several vehicles were damaged but no casualties were reported.