A gold mine in Mexico's violence-plagued Sonora state faced robbers arriving from both land and air this week, authorities say. Alamos Gold, a Canadian mining company, says five armed robbers subdued security guards as they were loading gold/silver alloy bars from the Los Mulatos mine onto a plane Wednesday morning, the Toronto Star reports. The robbers escaped with an estimated 160 pounds of precious metals on a light plane, believed to be a Cessna 206, that landed while the robbery was in progress. Highway robberies are common in the area, but this is believed to be the first that involved an aircraft, reports Mexico News Daily. The company says the loss is covered by insurance. (More gold mine stories.)