Once a Nazi has blown their whistle, other nearby Nazis will be alerted and actively hunt Sean. They will immediately open fire if Sean is in their line of sight. Also, a red radius will appear on the map, indicating the search radius.
The Alarm level increases gradually as Sean kills Nazis or destroying Nazi properties such as watch towers and their installations, while the alarm is present. However, the alarm level can still rise whenever Nazis are killed by other factors, such as involuntary ejections from their bikes or killed by Resistance soldiers. The size of the search radius will increase as the alarm level rises, making it more difficult to escape without being seen, unless in a disguise. To escape the Nazis, exit the search radius zone or use a hiding spot without being seen. The search zone will re-center and remains at Sean's current position if he is in a Nazi's line of sight. At the highest alarm level, however, Nazis will search the entire map and Sean can only use few hiding spots in order to remove the alarm level.
Any nearby Resistance members within inspired neighbourhoods can aid Sean in combat against the Nazis while the alarm goes off.
Sean can still wear a disguise even when the alarm is present, allowing him to easily go past the alerted Nazis. However, the last pursuit can continue if a Nazi has re-sounded the alarm after being fully suspicious.
To prevent an alarm being tipped off, kill the Nazi who is about to blow the whistle. Their halos will turn red when they do so. However, other nearby Nazis will also attempt blowing the whistle if one is killed. Hence, Sean must kill all the Nazi witnesses in order to prevent triggering the alarm.
Sean is unable to enter his hideouts when the alarm is present.
At the first alarm level, Wehrmacht soldiers in Sturmwagen cars and armed ZP750 motorbikes will be sent to hunt down Sean. If spotted by a Nazi manning the gun of their motorbike, they will immediately open fire at Sean.
At the second level, Nazis will begin carrying shotguns and takes slightly more damage before dying. Multiple soldiers will arrive in Bauer trucks and armed version of the Sturmwagen cars. There will be one soldier being the gunner of each Stuntwagen, immediately firing at Sean if spotted.
At the third level, Gestapo agents will join the hunt. They drive in black Gestapo cruisers armed with two machine guns attached to their cruisers. Also, multiple Nazi soldiers with MP44 machine guns and few gas-masked Nazis with flamethrowers will arrive in Half-Track APCs. At later point of the game, Fightback zones will begin appearing on the map, indicating that Sean can alternatively lose his heat completely by helping the Resistance fighting back against the Nazis.
At the fourth level, Terror Squad soldiers become involved in the hunt. They can take a lot of damage before dying and each of them carries the Terror MP60 machine guns. Couple of Nazi snipers will also be dispatched to compensate the Terror squad at long ranges. Sometimes, one of the soldiers is armed with Panzerschreck. In addition, a Nazi Zeppelin will intercept and shoot Sean from airbourne, even when Sean is not immediately discovered. If a Zeppelin is destroyed, another one will eventually arrive. Also, Nazis begin deploying in AP 33 APCs.
This is the highest alarm level. The Nazi soldiers dispatched will consist of purely Terror squad. Two additional types of Terror soldiers will be sent to hunt down Sean. One type carries the Terror shotguns and the other carries the Terror Flammenwerfers. Wulf tanks are dispatched and a war plane will now intercept and continuously fly back and forth while firing machine guns at Sean. War planes respawn shortly after one has been destroyed, similar to Zeppelins. Fightback zones will disappear from the map and the only way to remove this alarm level is to use the hiding places, marked green dots on the map. Before the "Europe's Most Wanted" perk is unlocked, there are only two hiding spots available during level 5 alarms; one is at the bar in the Eiffel Tower while the other is inside a well at the Morini farm. This alarm level isn't unlocked until at later point in the game.
- The "Europe's Most Wanted" perk enables Sean to use all hiding spots, even at highest alarm levels.
- Mechanics and black market dealers can also fightback against Nazis and they are immune to damage. However, Nazis will still continually attack them. Supporting characters (such as Santos, Vittore) can also fightback, although they are not invincible and if they die, the game slows down and a "Mission Failed" message will appear, even during outside of missions.
- In inspired areas of France you may sometimes see a woman who stands in one location and does not run during a alarm, if you can approach her without being sighted by the Nazis Sean can makeout with her to evade the alarm.