There was no tribulation against the saints. It was Romans punishing Jews. The real trib will be against Christians all over the Earth.
Most all Christians were converted jews in Jerusalem. They were warned by Christ's words to flee when they saw Jerusalem surrounded by armies. Jerusalem's defenders were all jews, many zealots. I doubt many Christians actually remained in Jerusalem. Many would have fled from Jewish persecutions of Christianized jews.
Jesus told his people to flee the whole region when the gentile Romans would come to capture and destroy the city and temple of the jews.
And He looked up and saw the rich men casting their gifts into the treasury, and He saw also a certain poor widow casting therein two mites. And He said, "In truth I say unto you that this poor widow hath cast in more than they all. For all these have of their abundance cast in unto the...
www.biblegateway.com
20 “And when ye shall see Jerusalem compassed with armies, then know that the desolation thereof is nigh.
21 Then let them that are in Judea flee to the mountains, and let them that are in the midst of it depart out, and let not them that are in the countries enter thereinto.
22 For these are the days of vengeance, that all things which are written may be fulfilled.
23 But woe unto them that are with child and to them that give suck in those days! For there shall be great distress in the land and wrath upon this people.
24 And they shall fall by the edge of the sword, and shall be led away captive into all nations. And Jerusalem shall be trodden down by the Gentiles until the times of the Gentiles be fulfilled.