Militants firing machine guns and grenades ambushed a police convoy Saturday and killed 9 officers in Russia's violent North Caucasus, officials said. Another 10 officers were wounded in the attack in Ingushetia's district of Sundja, which borders Chechnya, regional investigative committee spokeswoman Svetlana Gorbakova was quoted as saying by The Associated Press. Three of the four police vehicles in the convoy burned completely, the regional Interior Ministry said. The officers had been traveling from Chechnya in a joint anti-terrorism operation launched after a suicide bombing last week left Ingush President Yunus Bek Yevkurov badly injured and killed three of his bodyguards. Yevkurov remains in serious but stable condition in a Moscow hospital.