The death toll has risen after Hamas fired rockets into Israel from Gaza in a surprise attack and Israel declared war.

According to Israeli officials, at least 40 people have died in Israel and more than 700 people have been injured. The Palestinian Health Ministry said 160 people were killed in Gaza and over a 1,000 others were injured.

According to Al Jazeera, Israeli forces have surrounded a house in the Israeli settlement of Ofakim and negotiations are underway with Palestinian fighters who are allegedly holding hostages. According to the Jerusalem Post, dozens of hostages are being by Hamas in the Kibbutz Be’eru in southern Israel.

President Joe Biden was briefed Saturday "on the appalling Hamas terrorist attacks in Israel," according to the White House.

"Senior national security officials briefed the President this morning on the appalling Hamas terrorist attacks in Israel. The President will continue to receive updates and White House officials remain in close contact with Israeli partners," the White House said in a statement.

-ABC News' Fritz Farrow

U.S. Defense Secretary Lloyd Austin released a statement saying he is "closely monitoring" the situation in Israel and extended his condolences to the families of those who have lost their lives.

"Over the coming days the Department of Defense will work to ensure that Israel has what it needs to defend itself and protect civilians from indiscriminate violence and terrorism," Austin said.

Separately, a U.S. defense official said that Austin had a call with his team Saturday morning, including U.S. Centcom Commander Gen. Eric Kurilla. Israel falls under Centcom’s area of responsibility.

-ABC News' Luis Martinez

Israeli Prime Minister Benjamin Netanyahu made a video statement on social media, saying simply, “We are at war. We will win," in his first comments, made in Hebrew, after the attack.

"Citizens of Israel, we are at war, not in an operation or in rounds, but at war. This morning, Hamas launched a murderous surprise attack against the State of Israel and its citizens. We have been in this since the early morning hours. I convened the heads of the security establishment and ordered – first of all – to clear out the communities that have been infiltrated by terrorists," Netanyahu said. "This currently is being carried out. At the same time, I have ordered an extensive mobilization of reserves and that we return fire of a magnitude that the enemy has not known. The enemy will pay an unprecedented price. In the meantime, I call on the citizens of Israel to strictly adhere to the directives of the IDF and Home Front Command. We are at war and we will win it."

National Security Council spokesperson John Kirby avoided saying if the U.S. believed Israel's calls for civilians in Gaza to evacuate in the next 24 hours was possible but acknowledge that it was a "tall order" given how densely populated the area is.

"Well, I think we're going to be careful not to get into armchair quarterbacking the tactics on the ground by the IDF. What I can tell you is we understand what they're trying to do. They're trying to move civilians out of harm's way and giving them fair warning. Now, it's a tall order. It's a million people, and it's a very urban, dense environment, already a combat zone. I don't think anybody's underestimating the challenge here of affecting that evacuation," Kirby said in an interview on CNN Friday morning.

"But it's pretty clear that what they're trying to do is to the maximum extent possible avoid civilian casualties and also separate Hamas from the human shields. I mean, Hamas actually gave a counterorder telling Palestinians in Gaza to stay at home. Why? Because having human shields, they think, protects them," Kirby continued.

Asked about their efforts to secure a safe passage for civilians out of Gaza, Kirby reiterated that the U.S. is talking to Israel and Egypt but would not comment further on progress.

On the Rafah crossing specifically, Kirby said "So far it's still closed. But that doesn't mean were not going to still try as hard as we can to talk to the Israelis and Egyptians about getting it open and having some sort of safe passage out. It's important that we also continue to work to make sure that humanitarian assistance can get in. The United States has no intention of stopping our efforts to continue to deliver humanitarian assistance, but there has to be a path in, there has to be a path out."

Kirby had no update on the Americans who are believed to be held hostage in Gaza and could not confirm reports that 13 hostages have been killed by Israeli airstrikes, as Hamas has claimed.

-ABC News' Molly Nagle