Philo Judaeus Legatio Ad Gaium 128

[128] And some of those persons who are accustomed to pass their time in idleness and inaction, sitting around, occupied themselves in watching those who, as I have said before, were thus driven together and crammed into a very small space, as if they were a force which they were blockading; lest any one should secretly escape without their perceiving it. And a great many were designing to effect their escape from want of necessaries, disregarding their own safety from a fear that, if they remained, the whole body might perish with famine. So those men, expecting that they would endeavour to escape, kept a continual watch, and the moment that they caught any one, they immediately put him to death with every circumstance of insult and cruelty.