Israel-Gaza updates: 17 more hostages released, including 4-year-old American girl, officials say

Thirteen people are on a list of hostages who are expected to be released by Hamas in the Gaza Strip on Friday amid a temporary cease-fire, but it remains unclear exactly how many the militant group will free, according to Israel's Government Press Office.

During a press briefing on Friday morning, the Israeli Government Press Office said that the hostages who are released will be received by staff from the International Committee of the Red Cross, who will then take the hostages across the border and hand them over to the Israeli military. It was unknown which of Gaza's borders the hostages would cross -- either into Egypt or Israel.

From there, the Israel Defense Forces will identify each hostage who was released and the individuals will undergo medical examinations. Then they will be allowed to speak with their families via telephone, according to the Israeli Government Press Office.

The hostages will be transferred to one or more of five designated hospitals, depending on their medical needs. They will be physically reunited with their families at the hospitals, the Israeli Government Press Office said.

Among the freed hostages, children will not be debriefed by Israeli authorities but their mothers and other women who are capable will be, according to the Israeli Government Press Office.

-ABC News' Jordana Miller, Dana Savir and Morgan Winsor

The first pause in hostilities between Israel and Hamas in nearly seven weeks came into effect on Friday morning.

The four-day cease-fire started slightly later than the planned 7 a.m. local time, as the Israeli military carried out last-minute airstrikes on the war-torn Gaza Strip.

The Israel Defense Forces released a statement announcing the completion of "its operational preparations according to the combat lines of pause." Amid the early morning hours in the area of Gaza's largest hospital, Al-Shifa, Israeli troops destroyed a "route of underground tunnels and a number of tunnel shafts" that the IDF alleged was used by Hamas, which rules the enclave.

"The war is not over yet," the IDF added. "The suspension of fires for humanitarian purposes is temporary. The northern Gaza Strip area is a dangerous war zone and it is forbidden to move around."

"For your safety, you must remain in the humanitarian zone in the south of the Strip," the IDF continued. "It is only possible to move from the north of the Strip to its south via Salah al-Din Road. The movement of residents from the south of the Strip to the north will not be allowed in any way."

The release of some hostages being held by Hamas and other Palestinian militant groups in Gaza, in exchange for the release of some Palestinian prisoners in Israel, is expected to begin at 4 p.m. local time.

-ABC News' Bruno Nota, Joe Simonetti and Morgan Winsor

ABC News has learned more details about how the tentative release of Israeli hostages will play out from an Israeli source with direct knowledge of the current plan.

The Red Cross will pick up the hostages and transfer them through Egypt to Israel, the source said.

Once on the Israeli side a specially trained group of soldiers will identify them and cross-reference them from a list, according to the source.

Then the hostages will be offered a chance to speak to loved ones by phone, and then the adult hostages will be debriefed by the Shin Bet, the source said.

Women and girls released will be offered a rape kit, according to the source.

The hostages will be reunited with their families and be transported to several hospitals, the source said.

-ABC News' Matt Gutman

Israel Defense Forces spokesperson Daniel Hagari provided an update Thursday evening as families await the negotiated return of some of the hostages from Hamas.

He said they received the list of women and children who will be part of the first group released and the IDF has informed their families.

"This is a hard and tense evening for us all," Hagari said.

He reiterated that the current negotiation with Hamas is "not the end of the process of returning the hostages, but the beginning of it."

"Our hearts are with the families, and we will continue to accompany them, to keep them updated with the reliable information that we have," he said.

-ABC News' Dana Savir