At least 23 people have been killed after deadly clashes broke out on Saturday in Libya's capital between militias backed by its two rival administrations, signalling a return to violence amid a long political stalemate. The escalation threatens to shatter the relative calm Libya has enjoyed for most of the past two years. The oil-rich nation plunged into chaos following a NATO-backed uprising that toppled and killed long-time autocrat Moammar Gaddafi in 2011. The U.N. mission in Libya said the fighting involved “indiscriminate medium and heavy shelling in civilian-populated neighbourhoods” of Tripoli. An attempt in May by Bashagha to install his government in Tripoli triggered clashes that ended with his withdrawal from the capital.