U.S. Secretary of State Antony Blinken said part of the motivation for Hamas' latest attack on Israel may have been disrupting a potential normalizing of Israel-Saudi Arabia ties and said Washington will announce new assistance for Israel on Sunday.

Hamas fighters rampaged through Israeli towns as the country suffered its bloodiest day in decades on Saturday and battered Palestinians with air strikes in Gaza on Sunday, with hundreds reportedly killed on both sides. The spiraling violence threatens a major new Middle East war.

The attack by Hamas launched at dawn on Saturday represented the biggest and deadliest incursion into Israel since Egypt and Syria launched a sudden assault in an effort to reclaim lost territory in the Yom Kippur war 50 years ago.

"It wouldn't be a surprise that part of the motivation may have been to disrupt efforts to bring Saudi Arabia and Israel together, along with other countries that may be interested in normalizing relations with Israel," Blinken told CNN in an interview on Sunday.

Israeli Prime Minister Benjamin Netanyahu said last month he believed his country was on the cusp of peace with Saudi Arabia, predicting it could reshape the Middle East. Saudi Arabia, the home of Islam's two holiest shrines, has long insisted on the Palestinians' right to statehood as a condition of recognizing Israel - something that many members of Netanyahu's nationalist religious coalition have long resisted.

The United said on Sunday that Saudi-Israel normalization efforts should continue despite the latest attack.

"We think it would be in both countries' interests to continue to pursue this possibility," U.S. Deputy National Security adviser Jon Finer told Fox News Sunday.

FIGHTING CONTINUES IN GAZA

Blinken added the United States has also taken note of reports of several Americans killed and kidnapped in Israel and Washington is looking to verify the details and figures.

"We have reports that several Americans were killed. We're working overtime to verify that," Blinken said.

The secretary of state said details of new U.S. assistance for Israel will be made public later, as he labeled the attack on Israel as a "terrorist attack by a terrorist organization."

"We are looking at specific additional requests that the Israelis have made. I think you're likely to hear more about that later today," Blinken told CNN.

Blinken added there was relative calm on Sunday in most of Israel but intense fighting in Gaza, an Israeli-blockaded Palestinian enclave which has witnessed weeks of protests by youth groups due to long-time grievances related to the Israeli military occupation, the Palestinian national cause and prolonged economic strife.

He added that there was not yet any evidence seen by the United States of Iran being behind the latest attack in Israel but he noted the long-standing ties between Iran and Hamas, which governs Gaza.