The South African reggae musician, Lucky Dube, has been shot dead in front of his children in Johannesburg during an attempted car hijacking.He had been dropping his teenage son and daughter off in the suburb of Rosettenville on Thursday evening.Police say they were already out of the car when three shots were fired through a car window killing their father.Alongside Bob Marley, he was thought of as one of the great reggae artists - singing about social problems.He was also one of the apartheid regime's most outspoken critics.Correspondents say the killing has shocked South Africans who are already accustomed to one of the highest murder rates in the world