The U.S. State Department will be arranging chartered flights for American citizens who are currently in Israel, the White House announced Thursday.

The details on the flights are still being worked out, but those citizens will be flown out from Israel "to sites in Europe" starting Friday, White House National Security Council spokesman John Kirby told reporters.

"I would add that we're also exploring other options to expand the capacity of doing this, including exploring whether it's possible to help Americans leave by land and by sea," he said.

On ABC News Live at 8:30 p.m. on Thursday, Oct. 12, ABC News' James Longman, Matt Gutman and Ian Pannell look at the horrendous toll from Hamas' massacre, the Israelis and Palestinians caught in the middle and what comes next.

State Department spokesperson Matthew Miller said in a statement that the administration expects "these initial travel options to facilitate the safe departure of thousands of U.S. citizens per week."

"The overall security situation, availability and reliability of commercial transportation, and U.S. citizen demand will all influence the duration of this departure assistance," he said.

Miller added that "senior State Department officials are actively working with airline carriers and international partners on how best to provide additional options to U.S. citizens seeking to depart Israel or conduct onward travel to the United States."

The U.S. Embassy in Israel sent a message to Americans alerting them that "it will take some period of time to schedule everyone seeking to depart."

The message indicated that the expatriates would be transported by air to Athens, Greece, or Frankfurt, Germany, or by sea from Haifa to Cyprus.

"You will not be able to choose your destination. We will assign you to the next available flight or ship," the embassy said.

Pets will not be permitted on the flights, the embassy said.

The ex-pats will have to "sign an agreement to repay the U.S. government prior to departure," as required by U.S. law, and make their own arrangements for lodging in whatever country they arrive in, according to the embassy.

Delta Airlines said it's partnering with the U.S. government to help set up flights.

On Wednesday, the State Department elevated its advisory for travel for Israel and the West Bank to a Level 3, "reconsider travel," due to "terrorism and civil unrest," and it currently has a "do not travel" advisory for Gaza.

ABC News' Matt Gutman and Amanda Maile contributed to this report.