The Rafah border between Gaza and Egypt is not yet open to foreigners, including Americans, looking to evacuate. But if Americans who want to evacuate can move closer to the border crossing they should do so, because "there may be very little notice if the crossing opens and it may only open for a limited time," a U.S. Embassy spokesperson said.

We will continue to be in touch with private U.S. citizens to determine what assistance we may be able to provide," the spokesperson said.

A senior State Department official said the department is "in touch with a number of the roughly" 500 to 600 Palestinian-Americans "who have expressed interest in receiving information about leaving."

Hamas said nine hostages in Gaza have been killed by Israeli airstrikes over the last day.

The Israeli army and Israeli intelligence said they've targeted and killed Hamas commando forces leader Ali Qadi.

The United States did not ask Israel to hold off or delay a ground invasion of Gaza, ABC News has learned.

“U.S. officials have not asked Israel to slow down. But discussions did include the importance of taking into account the safety of civilians during any operations,” according to a U.S. official.

The official said the Israelis took it under advisement.

-ABC News' Luis Martinez

In remarks with Israeli Prime Minister Benjamin Netanyahu, Secretary of State Antony Blinken said at least 25 Americans had now been confirmed dead in Israel.

Netanyahu described some of the atrocities committed by Hamas.

"Hamas has shown itself to be an enemy of civilization: The massacring of young people in an outdoor music festival, the butchering of entire families, the murder of parents in front of their children and the murder of children in front of their parents. The burning of people alive, the beheadings," he said.

"Hamas should be treated exactly the way ISIS was treated," he said. "They shouldn't be spit out from the community of nations. No leader should meet them. No country should harbor them. And those that do should be sanctioned."

Blinken said he was speaking not only as an American diplomat, but as a Jew, a husband and a father of young children, saying it was impossible for him to look at photos of families killed "and not think of my own children."

"The same time that we've been shocked by the depravity of Hamas, we've also been inspired by the bravery of Israel citizens," he said. "The grandfather who drove over an hour to a kibbutz under siege, armed only with a pistol and rescued his kids and grandkids. The mother who died shielding her teenage son with her body, giving her life to save his -- giving him life for a second time."

Blinken remarked that some U.S. aid had already been delivered, and that more military aid was on his way. He said the administration would work with Congress to meet Israel’s additional needs and that bipartisan support for Israel was "overwhelming."

The secretary called on world leaders to condemn Hamas.

Blinken also reiterated that Israel "has the right -- indeed, the obligation -- to defend itself" but that it was "so important to take every possible precaution to avoid harming civilians."

-ABC News' Shannon Crawford