Israel’s national security advisor Tzachi Hanegbi and the U.S. announced that Gaza hostages will not be released before Friday, according to reports at Reuters.

Whitehouse spokesperson Adrienne Watson said logistical details for the release were still being worked on and that all is on track to implement from Friday morning.

The news comes on the heels of the agreement between Israel and Hamas to observe a ceasefire for a period of at least four days to enable humanitarian aid to reach afflicted areas and to free at least 50 hostages held by Hamas.

In exchange, Israel has agreed to release around 150 Palestinians jailed in the country.

It is not yet clear what time the ceasefire will commence, nor the release of the hostages, and reports from different sources have conflicting information. Qatar, which has been assisting in the negotiations, had a more optimistic view that the truce could come over the next few hours.