adrian,
The Abomination that causes desolation, that Jesus was speaking about, was the Roman armies, that first came in 66CE, then pulled away, then returned in 70CE and destroyed Jerusalem. Consider Matthew 24:15 also describes this Abomination that causes desolation as standing in a holy place. That Holy place was the Temple area in Jerusalem, where the Roman armies, unclean Gentiles, had partly undermined the Temple wall, before they pulled back and left.
Jesus told them that when they saw these things they were to leave Jerusalem as soon as the could. All Christians left Jerusalem as soon as the Roman armies left, with some going across the Jordan river to Pella, and other cities in the mountains East of the Jordan. By obeying what Jesus told them they were safe when the Roman armies returned in 70CE, and killed over a million Jews and carried off 96,000, of which many were killed later in the Coliseum, fighting animals, or professional Roman soldiers.
Agreed. There are other abominations but that is the most immediate one that Christ was referring to.