Timeline of surprise rocket attack by Hamas on Israel

As Israelis were wrapping up the seven-day-long Jewish festival of Sukkot on Saturday, the horrifying sounds of sirens echoed across Israel when thousands of missiles launched into the country by the Hamas militant group from Gaza streaked through the sky and began raining down on indiscriminate targets, sparking terror and leaving hundreds of bodies in the streets of cities and buildings decimated.

The surprise attack came just after sunrise on what Israeli Prime Minister Benjamin Netanyahu would describe as a "dark day" for his country and an Israeli military official deemed "our 9/11."

"We have begun the process of naming and counting the dead, both soldiers and civilians. We are talking about unprecedented numbers, numbers that up until two days ago seemed totally fictional and unimaginable," Lt. Col. Jonathan Conricus, a spokesperson for the Israel Defense Forces, told ABC News on Sunday.

As of Sunday afternoon, the death toll in Israel had climbed to more than 700 people, with another 2,100 injured. U.S. Secretary of State Antony Blinken said Sunday that American citizens are believed to be among the dead.

The Palestinian Health Ministry said 370 are dead and 2,200 others are injured in retaliatory strikes on Gaza.

The attack was launched on the 50th anniversary of the 1973 Yom Kipper War that pitted Israel against Egypt and Syria.

Here is a timeline of events in the rapidly changing conflict enveloping Israel and the Palestinian Gaza Strip territory:

A barrage of rockets

Oct. 7, 6:30 a.m. in Israel

Air raid sirens began sounding in Jerusalem around 6:30 a.m. local time, warning citizens of the attack in progress and to immediately take cover. An estimated 2,200 rockets were fired toward southern and central Israel, including Tel Aviv and Jerusalem, by the Hamas militants, according to the Israel Defense Forces. Meanwhile, Hamas claimed at least 5,000 rockets were fired, all landing in southern and central Israel.

One missile slammed into a hospital in the Israeli coastal town of Ashkelon, Israeli officials said.

Armed Hamas militants, many on motorcycles, storm blockaded areas of the Gaza Strip, shooting at Jewish settlers in the Gaza Strip, officials said. Video footage surfaces of Hamas militants taking Israeli citizens hostage near the Gaza border.

In one of its first public messages, the IDF said Saturday morning, "Over the past hour, the Hamas terrorist organization launched massive barrages of rockets from Gaza into Israel, and its terrorist operatives have infiltrated into Israel in a number of different locations in the south."

Oct. 7, shortly after the attack begins

Mohammed Deif, commander in chief of the Hamas' military arm Al Qassam Brigades, releases a video statement claiming responsibility for the attack.

"The Zionist colonial occupation occupied our Palestinian homeland and displaced our people, destroyed our towns and villages, committed hundreds of massacres against our people, killing children, women and elderly people and demolishing homes with their inhabitants inside in violation of all international norms, laws and human rights conventions," Mohammed Deif said in his statement.

'Israel is at war'

Oct. 7, about 10:30 a.m. local time

Israeli jet fighters launched retaliatory strikes in Gaza. Video surfaces of a high-rise residential building in central Gaza City being bombed and flattened by Israeli fighters.

Oct. 7, around 11:30 a.m. in Israel

Netanyahu makes his first public statement, telling his country, "Israel is at war."

"This is not a so-called military operation, not another round of fighting, but war," Netanyahu says.

Oct. 7, around 8:30 p.m. ET

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

"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.

Oct. 7, around 9:30 a.m. ET

The White House announces that President Joe Biden has been briefed by senior national security officials "on the appalling Hamas terrorist attacks in Israel."

Oct. 7, just after 10 a.m. ET

U.S. Secretary of State Antony Blinken issues a statement condemning Hamas' attack on Israel, saying the U.S. will "remain in close contact with our Israel partners."

"The United States unequivocally condemns the appalling attacks by Hamas terrorists against Israel, including civilians and civilian communities. There is never any justification for terrorism. We stand in solidarity with the government and people of Israel, and extend our condolences for the Israeli lives lost in these attacks," Blinken said in a statement.

Oct. 7, around 11 a.m. ET

The White House announces that Biden had spoken with Netanyahu, telling the prime minister the U.S. "condemns" Hamas' assault on Israel.

"I made clear to Prime Minister Netanyahu that we stand ready to offer all appropriate means of support to the Government and people of Israel. Terrorism is never justified. Israel has a right to defend itself and its people. The United States warns against any other party hostile to Israel seeking advantage in this situation. My Administration's support for Israel's security is rock solid and unwavering," Biden said in a televised statement.

'We will win'

Oct. 7, around 5 p.m. ET

Netanyahu makes a televised address in Israel, repeating his earlier statement that Israel is at war and adding, "We will win."

"This morning, Hamas launched a murderous surprise attack against the State of Israel and its citizens," Netanyahu said. "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. 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."

30 Israeli police killed in fighting

Oct. 8, around 5 a.m. ET

At least 30 Israeli police officers were killed in the fighting, mainly in Sderot, Israel, where Hamas gunmen took control of the police station.

Israeli officials announce that fighting is ongoing Sunday morning in six places, including Sderot -- which sits just two miles from the border with Gaza -- and that a rocket injured four people on Sunday morning.

Oct. 8, around 9 a.m. ET

The Israeli government confirmed that a number of civilians and soldiers have been taken hostage. At least 100 Israeli citizens and soldiers are being held hostage by Hamas fighters, Israel's Government Press Office said Sunday.

Blinken says on CNN's "State of the Union" and NBC's "Meet the Press" that the State Department is trying to confirm reports that Americans are among those killed or taken hostage.

Blenkin tells ABC's "This Week" anchor George Stephanopoulos that the U.S. has pledged its full support to Israel.

"This is a massive terrorist attack that is gunning down Israeli civilians in their towns, in their homes, and as we've seen, so graphically, literally dragging people across the border with Gaza, including a Holocaust survivor in a wheelchair, women and children," Blinken said on "This Week."

He adds, "The world should be revolted at what it's seen."

Oct. 8, around 1 p.m. ET

Israeli health officials announce that more than 700 people are dead in Israel and over 2,100 others injured. The Palestinian Health Authority said there are 370 people dead in Gaza and 2,200 others injured.