Police in Guinea's capital fired warning shots when they clashed with stone-throwing protesters on Monday as tensions escalated over a general strike called by unions trying to oust the West African country's president, Reuters reported. Union leaders threatened to halt Guinea's important bauxite industry as they sought to increase the pressure on President Lansana Conte to step aside. In street clashes in Conakry on the sixth day of the nationwide stoppage, riot police fired teargas at groups of rioting youths who burned tyres and smashed car windows, police and witnesses said. Police said they made several arrests, including some protesters found to be carrying firearms, before calm returned to the worst-hit neighbourhoods. "They fired on us. We've seized some firearms along with protesters. We'll be investigating where these arms came from," a senior police officer, who asked not be named, told Reuters. He said one group of demonstrators had tried to break into a police station to seize arms.