To do so, the officers must complete three days of training on their use on patrol, have their guns inspected by the department and carry them in locked cases, The Tennessean reported Tuesday.
Metro Police Chief Steve Anderson said the policy change is in response to the mass shootings in Aurora, Colo., and Newtown, Conn., the Nashville newspaper said. In both, the alleged shooters used AR-15s.
"It has become increasingly clear that a pistol and shotgun may not be enough for an officer to stop a threat to innocent citizens," he said. "This policy change is in the best interest of public and officer safety."
The Rev. Philip Breen of St. Ann Catholic Church, who is leading a campaign to restrict ownership of semiautomatic weapons and high-capacity magazines, said he supports allowing police to use the weapons.
"They are the lawful authorities and are trained to use them," Breen said. "In fact, they probably need to protect themselves in this day and time."