34 Then ten thousand of Israel’s able young men made a frontal attack on Gibeah. The fighting was so heavy that the Benjamites did not realize how near disaster was.

Read Judges 20:34 Using Other Translations

And there came against Gibeah ten thousand chosen men out of all Israel, and the battle was sore: but they knew not that evil was near them.
And there came against Gibeah 10,000 chosen men out of all Israel, and the battle was hard, but the Benjaminites did not know that disaster was close upon them.
There were 10,000 elite Israelite troops who advanced against Gibeah. The fighting was so heavy that Benjamin didn’t realize the impending disaster.