A.T. Robertson Commentary Acts 21:32

"And forthwith he took soldiers and centurions, and ran down upon them: and they, when they saw the chief captain and the soldiers, left off beating Paul." — Acts 21:32 (ASV)

Forthwith (εξαυτης). Common in the Koine (εξ αυτης, supply ωρας, hour).

He took (παραλαβων). See verses 24,26.

Centurions (εκατονταρχας). See on Lu 7:2 for discussion. Plural shows that Lysias the chiliarch took several hundred soldiers along (a centurion with each hundred).

Ran down (κατεδραμεν). Effective second aorist active indicative of κατατρεχω. From the tower of Antonia, vivid scene.

And they (ο δε). Demonstrative use of ο. The Jewish mob who had begun the work of killing Paul (verse 31).

Left off beating Paul (επαυσαντο τυπτοντες τον Παυλον). The participle with παυομα describes what they were already doing, the supplementary participle (Robertson, Grammar, p. 1121). They stopped before the job was over because of the sudden onset of the Roman soldiers. Some ten years before in a riot at the passover the Roman guard marched down and in the panic several hundred were trampled to death.