Albert Barnes on Luke 21:35

As a snare. In Matthew and Mark Jesus compares the suddenness with which these calamities would come to the deluge coming in the days of Noah. Here he likens it to a snare. Birds are caught by a snare or net. It is sprung on them quickly, and when they are not expecting it. So, says he, shall these troubles come upon Judea. The figure is often used to denote the suddenness of calamities, Ps 69:22, Rev 11:9, Ps 124:7, Is 24:17.

(f) "For as a snare" 1Thes 5:2, 2Pet 3:10, Rev 16:15