Mexican authorities arrested a woman guarding an arsenal that included the first anti-aircraft machine gun seized in Mexico, police said Tuesday, as the army announced the capture of an alleged top drug cartel lieutenant. The arsenal belonged to a group linked to the powerful Beltran-Leyva drug cartel, federal police coordinator Gen. Rodolfo Cruz said. It also included ammunition, five rifles, a grenade and part of a grenade launcher. Mexican drug cartels, battling a fierce crackdown by soldiers and federal police, have increasingly gotten hold of higher-powered weapons, even military-grade arms such as grenades and machine guns. That has left police - particularly state and municipal forces - grossly outgunned, and many officers have quit following attacks. Cruz said the confiscated .50-caliber, anti-aircraft machine gun can fire 800 rounds per minute and is capable of penetrating armor from more than 5,000 feet (1,500 meters). Police on a routine patrol Monday found the gun fitted atop an SUV at a house in northern Sonora state.