Dozens of Israeli fighter jets have struck several targets in the Al Forqan area of the Gaza Strip, which serves as a hub for Hamas, the Israel Defense Forces said. Massive blasts were seen igniting over the area at the same time.

Many of the operations against Israel this weekend were launched from the Al Forqan area, the IDF said.

-ABC News' Jordana Miller

Lt. Col. Jonathan Conricus, spokesperson for the Israel Defense Forces, called Hamas' attack "unprecedented," and said the assault will be "followed by an unprecedented Israeli response."

"I could not imagine at that time [when the incursion began Saturday] that Hamas would have the audacity … to do what they have done," he told ABC News Monday. "To launch such an unprecedented, brutal, merciless attack on Israeli citizens. … And cause the amount of casualties that Israel has never experienced ever in its history."

In Israel, at least 700 people have died and more than 2,300 others have been injured since Saturday.

The Israel Defense Forces has since launched retaliatory airstrikes on Gaza. At least 560 people have died and another 2,900 have been injured in Gaza since Saturday, Palestinian authorities said.

The IDF said it's struck 130 targets in the last three hours.

Personnel at the U.S. Embassy in Israel are now under a curfew from 8 p.m. to 6 a.m. and "are urged to stay as close to home as possible outside the curfew hours," the U.S. Embassy said in a new alert.

In addition to a ban on personal travel to Gaza and the surrounding areas, the new alert said all U.S. government personnel are also prohibited from personal travel to the West Bank.

"U.S. citizens in Israel who have family members missing in the Gaza periphery can go to the Israel National Police’s combined assistance center at 4 HaNegev Street in Airport City," the alert said.

-ABC News' Shannon Crawford

Israel Defense Forces' helicopter gunships are attacking Lebanese territory on Monday after the IDF said two rockets were fired from Lebanon.

The Lebanese army said, "The outskirts of the towns of Al-Dhaira and Aita Al-Shaab and other border areas are being subjected to air and artillery bombardment by the Israeli enemy. The Army Command calls on citizens to take the utmost precaution and caution and not to go to areas adjacent to the border in order to preserve their safety."

Of the two rockets fired from Lebanon toward Israel, one of the rockets fell in Lebanese territory and no injuries were reported.

As Americans inside Gaza wait for the Rafah border crossing between Egypt and Gaza to open, a senior State Department official said that Egypt has informed the U.S. that “there are acute security threats" preventing U.S. officials and others from aiding Americans inside Gaza.

The official added that the State Department has placed a team on the Egypt side of the border "as close to the border as conditions permit."

Egyptian Foreign Minister Sameh Shoukry said Monday that Israel has not allowed the opening of the Rafah border crossing from the Gaza side.

Shoukry said, since the crisis broke out, Egypt "has been seeking to keep the crossing operational and in a way that allows the entry of humanitarian aid."

"Until now, unfortunately, the Israeli government has not taken a position to allow the opening of the crossing from the Gaza side for the entry of aid or the exit of nationals of [other] countries," Shoukry said. "We are ready and Egyptian authorities on the border are ready to get aid in and get nationals of third countries out."

He added that Egypt aims to keep normal operation of the border "for the entry of Palestinians with medical needs or the normal movement between the Strip and Egypt."

-ABC News' Shannon Crawford