The government began a gun buyback campaign on Friday that officials hope will take more than one million guns off the streets by the end of the year. The campaign started one month after a gunman shot and killed 12 children in a Rio de Janeiro school before killing himself. In similar campaigns in 2003 and 2009, 1.1 million firearms were turned in. The Justice Ministry says on its Web site that gun owners can turn in their guns and ammunition with no questions asked and will receive the equivalent of up to $190. The weapons will be immediately disabled with a hammer and later melted down.