LONDON: British Prime Minister David Cameron called for a fightback against extremism on Monday in response to a mass shooting in Tunisia that killed at least 38 people including many British tourists. “To our shock and grief we must add another word: resolve. Unshakeable resolve. We will stand up for our way of life,” Cameron wrote in British newspaper the Daily Telegraph calling for “a response at home and abroad.” The number of British victims may rise to more than 30 from the official toll of 15, the BBC reported Monday. It was the worst loss of British life in a terror attack since 52 people died in suicide bombings on the London transport system on July 7, 2005.