Bandits, also known as raiders, are the largest external threat to the family. They are a group of people that take control of an area, coming in only after family members have sent out too many expeditions, and they are much more likely to come if expeditions are sent out one after the other, including events where the player is prompted to send someone outside the shelter. The game will let you know if the bandits are close after a family member returns from an expedition, letting the player know that the family member was followed. There is no set number of times the scavenging family member must be followed; after the first time, the player has only about 20 days before the bandits take control of the area.
The game lets the player know if bandits have taken control of the area on the "prepare for expedition" screen. At this point, it is extremely dangerous for a character to go on an expedition, as they are extremely likely to be captured or killed by raiders.
Once the bandits have moved in, the family is not safe in the shelter, either, but only if a family member enters the shelter after the bandits take control. Bandits will periodically come to the shelter and the family will have to defend themselves. If they are incapable of doing so, the bandits will kidnap family members, starting with Mary Jane, then Timmy, then Dolores, then Ted, or raid the shelter and leave it empty, leaving the family extremely likely to die of dehydration; or cause an instant Game Over.
If a character was captured by raiders, it is possible that he or she can be rescued via the "Payback time." events.