Two persons were killed when a bus, carrying at least 50 people, overturned on the Lucknow-Agra Expressway in Uttar Pradesh on Tuesday. Five persons were critically injured and several others suffered minor injuries, police said. The bus was on its way to Bihar from Rajasthan. A huge crowd gathered at the spot and an ambulance waited to carry the injured to hospital. The bodies have been sent for post-mortem. The reason behind overturning of the bus is not yet known.