2 Maccabees 10:17

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

2 Maccabees 10:17 In-Context

15 Not only this, but the Idumeans themselves controlled certain strategic fortresses and were constantly harassing the Jews. They welcomed those who fled from Jerusalem and did everything they could to keep the country in a perpetual state of war.
16 So Judas Maccabeus and his men, after offering prayers for God's help, rushed out and made a vigorous attack against the Idumean fortresses.
17 They beat back those who were defending the walls and captured the fortresses, killing everyone they found, a total of about 20,000 people.
18 About 9,000 of the enemy, however, managed to take refuge in two easily defended forts, with everything they needed to withstand a siege.
19 Judas had to go on to some other places in the country, where he was more urgently needed, but he left behind Simon and Joseph, together with Zacchaeus and his men. This force was large enough to continue the siege,
Scripture taken from the Good News Translation - Second Edition, Copyright 1992 by American Bible Society. Used by Permission.