Acts 5:24

‘Now when the captain of the temple and the chief priests heard these words, they were much perplexed concerning them as to how far this would grow.'

The news came through to the captain and the chief priests, who were seemingly not sitting at this point in the tribunal, or at least were sitting apart where they could be consulted privately. The words gave the chief priests food for thought. The captain of the Temple was second only to the High Priest (which might suggest that the High Priest was not involved in the discussions. Alternately the captain might be mentioned because he was the one to whom the report would be made, an indication of authenticity). And as they considered the matter they were perplexed and worried. They did not like these strange things that kept happening when these men were involved. How far was this thing going to grow?

Underlying these last words is a recognition that this was something uncanny, which should have required thought. But their hearts were hardened. Instead of acknowledging God's hand in it they determined that they must get rid of these men one and for all.