A gun locking and unlocking device, which may be configured to be disposed on or in a gun to alternatively prevent or enable firing, includes a data receiver, a data memory and a logic device for determining whether security data received by the receiver is the same, or substantially the same, as data stored in the data memory. One or more separate electronic gun key devices are provided to transmit security data and gun control signals to the data receiver of the gun lock device. The logic device responds to the gun control signals transmitted by one of the gun key devices to lock or unlock the gun, respectively, when the received security data and the security data stored in memory are substantially similar. The logic device also automatically locks the gun when the gun is located more than a prescribed distance from the gun key device. In case of emergency the gun security feature can be bypassed (overridden) by transmitting a gun control command to either lock or unlock the gun.