Israel has agreed to a hostage swap with Hamas, but it's unclear where all the people kidnapped from Israel are.

The assault on Gaza will be paused four days, in exchange for 50 women and children kept by the Palestinian military group.

Israel says it will return three Palestinians for every hostage - and each 10 hostages released will extend the pause on hostilities another day.

Times of Israel US Bureau Chief Jacob Magid says some hostages are being kept in underground tunnels.

"And not all of them are even with Hamas, there are roughly 30 hostages that are also being held alive in post-Islamic Jihad."

LISTEN ABOVE