Each guard has radio with him.
Trigger[ | ]
A guard will turn on his radio upon hearing a gun sound or seeing an agent. It takes some time for a guard to turn on his radio, during which he cannot attack.
Outcome[ | ]
He will turn off his radio after searching without finding anything. The alert level slightly rises after one guard turns off his radio.
If a guard is killed with radio on, his body will be instantly found. It is the same outcome as when a body is found.