Ukraine's acting President Oleksander Turchinov has called an emergency meeting with the heads of security services as pro-Russian protesters stormed government buildings in a number of major cities in the country's east, calling for referenda on joining Russia. In Donetsk, 80km west of the Russian border, a group of 50 people, including many in masks carrying sticks and stones, moved away from a crowd of 2,000 rallying the main city square on Sunday and surged into the provincial government building and smashed windows. Al Jazeera's Kim Vinnell reports from Donetsk.