New Revised Standard Version
Likewise, when all the Israelites who had gone into hiding in the hill country of Ephraim heard that the Philistines were fleeing, they too followed closely after them in the battle.

Contemporary English Version
Many Israelites had been hiding in the hill country of Ephraim. And when they heard that the Philistines were running away, they came out of hiding and joined in chasing the Philistines.

New American Bible
Likewise, all the Israelites who were hiding in the hill country of Ephraim, hearing that the Philistines were fleeing, kept after them in the battle.

Douay-Rheims Bible
And all the Israelites that had hid themselves in mount Ephraim, hearing that the Philistines fled, joined themselves with their countrymen in the fight. And there were with Saul about ten thousand men.

And all the Israelites that had hid themselves in mount Ephraim, hearing that the Philistines fled, joined themselves with their countrymen in the fight. And there were with Saul about ten thousand men.

hid themselves

1 Samuel 13:6 And when the men of Israel saw that they were straitened (for the people were distressed), they hid themselves in caves, and in thickets, and in rocks, and in dens, and in pits.

1 Samuel 31:7 And the men of Israel, that were beyond the valley, and beyond the Jordan, seeing that the Israelites were fled, and that Saul was dead, and his sons, forsook their cities, and fled: and the Philistines came and dwelt there.

the battle The LXX.