American citizens in the Gaza Strip may be allowed to leave on Saturday, according to a US official with knowledge of the situation.

Still, while Israel and Egypt have said they can exit via the Rafah crossing between Gaza and Egypt, it’s unclear if Hamas will agree to that, said the official, who declined to be named discussing private talks.

Israel announced a “safe passage” on Saturday as it urges more civilians to move from the north of Gaza — where the Israeli military is concentrating the bulk of its operations — to the south. It ends at 4 p.m. local time (2 p.m. UK).

The intention is to have the border crossing open from noon to 5 pm local time, the official said.

Israel Latest: Army Urges More People to Move to South of Gaza

Hamas, backed by Iran and designated a terrorist group by the US, rules Gaza. The Rafah crossing is in the south of the territory.

People in Gaza are bracing for a full-scale ground assault by Israel’s troops as the country continues to wage war on Hamas following the group’s deadly attacks last week.

A Million Gazans Have Nowhere to Hide From Coming Israel Troops

The US has been in touch with roughly 500-600 of its citizens in Gaza, the official said, stressing they could only speak about their efforts on behalf of Americans.

It’s unclear if Egypt and Israel will allow other foreigners to leave Gaza.

(Updates with more detail.)