US Secretary of State Antony Blinken says his country is trying to verify reports of missing and dead Americans overseas after Hamas attacked Israel, triggering a crisis in the region.

“We have reports that several Americans were killed. We’re working overtime to verify that. At the same time, there are reports of missing Americans and there again, we’re working to verify those reports,” Blinken told CNN’s Dana Bash on “State of the Union.”

He said an additional aid to Israel in response to the attack could be announced soon.

“We’re 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.

The top US diplomat added that President Joe Biden’s direction was to “make sure that we’re providing Israel everything it needs at this moment to deal with the attacks from Hamas.”

The Israeli government has confirmed that at least 100 of its citizens are currently held captive in Gaza.

Israel’s Government Press Office confirmed the development by sharing an infographic on Facebook where it said “100+ kidnapped, 2,000+ injured, 600+ murdered.”

Until now Israel has refused to confirm the number of civilians or soldiers being held hostage, reported The Times of Israel.

Meanwhile, the death toll due to the attack conducted by Hamas on the Israeli border community has touched 600, media reports said.

A spokesperson for ZAKA, a volunteer group that handles dead bodies and human remains after terror attacks, tells Hebrew media as quoted by The Times of Israel that more than 600 Israelis have been killed so far.

The Israeli government formally declared war on Hamas on Sunday, a day after the deadly attack was carried out by the group.

Israeli jets carried out “intense” airstrikes on targets in Gaza Sunday afternoon, shortly after Prime Minister Benjamin Netanyahu’s office announced that the security cabinet had voted Saturday evening to put the country officially at war, meaning it can carry out “significant military activities", The Times of Israel reported.

On Saturday, the Palestinian Islamic Resistance Movement (Hamas), which controls Gaza, showered Israel with thousands of rockets in a rare surprise attack.