Good News Translation
They beat back those who were defending the walls and captured the fortresses, killing everyone they found, a total of about 20,000 people.

Contemporary English Version
They made violent attacks on them and forced the enemy soldiers to retreat from their positions on the walls. Then after they had captured these places, they killed everyone they could. At least 20,000 of their enemies died.

Douay-Rheims Bible
And assaulting them with great force, won the holds, killed them that came in the way, and slew altogether no fewer than twenty thousand.

And assaulting them with great force, won the holds, killed them that came in the way, and slew altogether no fewer than twenty thousand.

2 Maccabees 10:15
And the Jews that occupied the most commodious holds, received those that were driven out of Jerusalem, and attempted to make war.

2 Maccabees 10:16
Then they that were with Machabeus, beseeching the Lord by prayers to be their helper, made a strong attack upon the strong holds of the Idumeans:

2 Maccabees 10:18
And whereas some were fled into very strong towers, having all manner of provision to sustain a siege,

2 Maccabees 10:19
Machabeus left Simon and Joseph, and Zacheus, and them that were with them, in sufficient number to besiege them, and departed to those expeditions which urged more.