Mosul - A 12-year-old Iraqi boy was killed and four other bystanders were seriously wounded as United States troops clashed with insurgents in Iraq's main northern city late on Wednesday killing four of them, police and medics said. Two US soldiers were also wounded in the twin clashes in Mosul city centre, police said. In the first exchange, insurgents threw hand grenades and opened fire at a US Humvee in the Hay Masraf district and soldiers returned fire killing one of them, said police captain Fathi Salah Zubeidi who witnessed the attack. In the second, insurgents attacked US troops with...