A.T. Robertson Commentary Acts 21:31

"And as they were seeking to kill him, tidings came up to the chief captain of the band, that all Jerusalem was in confusion." — Acts 21:31 (ASV)

As they were seeking to kill him (ζητουντων αυτων). Genitive absolute of ζητεω, to seek, without αυτων (they). This was their real purpose.

Tidings (φασις). From φαινω, to show. Old word for the work of informers and then the exposure of secret crime. In LXX. Here only in the N.T.

Came up (ανεβη). Naturally in the wild uproar. The Roman guard during festivals was kept stationed in the Tower of Antonia at the northwest corner of the temple overlooking the temple and connected by stairs (verse 35).

To the chief captain (τω χιλιαρχω). Commander of a thousand men or cohort . His name was Claudius Lysias.

Of the band (της σπειρης). Each legion had six tribunes and so each tribune (chiliarch) had a thousand if the cohort had its full quota. See on 10:1; 27:1. The word is the Latin spira (anything rolled up). Note the genitive σπειρης instead of σπειρας (Attic).

Was in confusion (συνχυννετα). Present passive indicative of συνχυννω (see verse 27, συνεχεον). This is what the conspirators had desired.