Is this speaking of a literal flood, or just that the end will be sudden and destructive like a flood? Did this happen in AD70 when the Romans armies destroyed the city of Jerusalem, or does it refer to a future event?
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
The use of 'flood' in the verse is very likely figurative. A similar term in Dan 11:22, the closest cross-reference for the verse, means to figuratively 'sweep away'.
"Then an overwhelming army will be swept away before him; both it and a prince of the covenant will be destroyed." Dan 11:22
Other verses also use the metaphor of a flood for complete/sudden destruction:
Ps 90:5 "You carry them away as with a flood;..."
Isa 8:7-8 "Now therefore, behold, the Lord brings up on them the waters of the river, strong and many, even the king of Assyria, and all his glory: and he shall come up over all his channels, and go over all his banks..."