An exemplary method includes operating an access control device in a standalone mode, which involves controlling a locked/unlocked state of the access control device locally, and operating a wireless transceiver of the access control device in a lower-power state in which the wireless transceiver is operable to receive a lockdown signal from an external device. The method further includes operating the access control device in a networked lockdown mode in response to receiving the lockdown signal from the external device. Operating the access control device in the networked lockdown mode involves placing the access control device in a locked state, establishing a wireless communication connection with the external device via the wireless transceiver while operating the wireless transceiver in a higher-power state.