Now trapped inside the city of Jerusalem the people of Israel destroyed their own food supply that would have been sufficient for a siege of Roman for many years.
Fighting broke out inside the city between the warring factions of Jews. The innocent were killed. Nothing was done for the wounded. And Dead bodies lay unburied. The madness in side the city of Jerusalem was so great they set houses on fire that were full of corn, and all other provisions. They polluted their own drinking water
4. And now there were three treacherous factions in the city, the one parted from the other. Eleazar and his party, that kept the sacred first-fruits, came against John in their cups. Those that were with John plundered the populace, and went out with zeal against Simon.
This Simon had his supply of provisions from the city, in opposition to the seditious. When, therefore, John was assaulted on both sides, he made his men turn about, throwing his darts upon those citizens that came up against him, from the cloisters he had in his possession, while he opposed those that attacked him from the temple by engines of war; and if at any time he was freed from those that were above him, which happened frequently, from their being drunk and tired, he sallied out with a great number upon Simon and his party; and this he did always in such parts of the city as he could come at, till (he set on fire those houses that were full of corn, and of all provisions).* (1) The same thing was done by Simon, when, upon the others' retreat, he attacked the city also; as if they had, on purpose done it to serve the Romans, (by destroying what the city had laid up against the Siege), and by thus cutting off the nerves of their own power.
Accordingly, it so came to pass, that all the places that were about the temple were burnt down, and were become an intermediate desert space, ready for fighting on both sides; and that almost (all the corn was burnt, which would have been sufficient for a siege of many years). So they were taken by the means of famine, which it was impossible they should have been, unless they had thus prepared the way for it by this procedure. Josephus Book V, Chapter I, Section 4 (Entire)
This destruction of such a vast quantity of corn and other provisions, as was sufficient for many years, was the direct occasion of that terrible famine, which consumed incredible numbers of Jews in Jerusalem during its siege.
These unbelieving Jews did not heed the warning of Jesus. Jesus said "But pray that your flight may not be on a Sabbath" Matthew 24:20. The reason Jesus said to pray that the city would not be destroyed beginning on Sabbath day is obvious to anyone living within the city of Jerusalem.
Jerusalem was a Jewish dominated town which kept 100% of the law of Moses up to 70AD. The Gates of the city would be closed on the Sabbath: (Nehemiah 13:15-22) This would hinder the Lord's instructions to the Christians to GET OUT OF THE CITY before the Roman armies destroyed the city as Jesus said in Luke 21:20 NKJV “But when you see Jerusalem surrounded by armies, then know that its desolation is near. 21 Then let those who are in Judea flee to the mountains, let those who are in the midst of her depart, and let not those who are in the country enter her. 22 For these are the days of vengeance, that all things which are written may be fulfilled. 23 But woe to those who are pregnant and to those who are nursing babies in those days! For there will be great distress in the land and wrath upon this people. 24 And they will fall by the edge of the sword, and be led away captive into all nations. And Jerusalem will be trampled by Gentiles, until the times of the Gentiles are fulfilled.
Jesus lists 3 things that would hinder fleeing the city: Matthew 24:15-21 Pregnant or Nursing mothers hindered for obvious reasons. Winter would hinder because of exposure to cold and snow. Sabbath day because the gates of the Jewish controlled city of Jerusalem would be locked and they could not get out!