noun
vigilante group; neighborhood watch; self-defense group
A group organized by local residents to patrol and protect their community, often formed in response to crime or disaster.
その町では、夜間のパトロールのために自警団が組織された。
In that town, a neighborhood watch was organized for nighttime patrols.
災害後、住民たちは自警団を作って安全
After the disaster, the residents formed a self-defense group to maintain safety.
消防団 is a volunteer fire corps, whereas 自警団 focuses on general community safety and crime prevention.
Compound of 自 (self), 警 (guard/warn), and 団 (group).