to fly quickly and suddenly downwards, especially in order to attack sb/sth
[I] ~ (on sb/sth)(especially of police or soldiers 尤指警察或士兵) to visit or attack sb/sth suddenly and without warning 突然袭击；突击搜查；突然行动
noun
an act of moving suddenly and quickly through the air in a downward direction, as a bird does （鸟等的）向下猛冲，俯冲 SYN dive
~ (on sth/sb)an act of arriving somewhere or attacking sth/sb in a way that is sudden and unexpected 突然袭击；突击搜查；突然行动 SYN raid
Large quantities of drugs were found during a police swoop on the star’s New York home.
警方对这个明星在纽约的住所进行突击搜查，发现了大量毒品。
at/in one fell swoop
all at the same time; in a single action, especially a sudden or violent one 一下子；一举