swoop down on (someone or something)
1. To move down in a sudden plunging sweep to seize or land on someone or something. The falcon swooped down on its trainer's arm. The pelicans hover over the bay, swooping down on fish that venture too close to the surface of the water.
2. To descend on someone or something very quickly and suddenly, as to attack or grasp them or it. The children all swooped down on the pile of candy that fell from the broken piñata. Several police officers swooped down on the suspect.
swoop down (up)on someone or something
1. Lit. to dive or plunge downward on someone or something. The eagle swooped down upon the lamb.
2. Fig. [for someone] to pounce on and consume something. The children swooped down on the ice cream and cake.