Albert Barnes Commentary Luke 21:35

"for [so] shall it come upon all them that dwell on the face of all the earth." — Luke 21:35 (ASV)

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, he says, these troubles shall come upon Judea. The figure is often used to denote the suddenness of calamities, Psalms 69:22; Revelation 11:9; Psalms 124:7; Isaiah 24:17.