Tel Aviv: Israeli Prime Minister Benjamin Netanyahu has said Hamas has started a cruel, evil war and the Israel Defence Forces (IDF) will use all its strength to destroy Hamas' capabilities.

"Hamas forces invaded Israeli territory this morning, on the morning of a holiday and Shabbat, and murdered innocent civilians, children and the elderly. Hamas started a cruel and evil war. We will win this war, but the price is too heavy to bear. This is a very difficult day for all of us," the Israeli PM wrote on 'X' on Sunday.

A major upheaval took place in the Middle East on Saturday, when the Hamas terror group launched a "surprise attack", firing a barrage of rockets into southern and central Israel.

According to the latest developments, 250 people have been killed, at least 1104 people are injured and several Israelis have been held as hostages in Gaza, the Times of Israel reported citing officials.

Netanyahu said: "Hamas wants to murder us all. It is an enemy who murders children and mothers in their homes, in their beds. An enemy who kidnaps the elderly, children, girls. Murderers who slap and slaughter our citizens, our children, who all in all went out to spend the holiday."

He said that what happened in Israel on Saturday, he will make sure that it does not happen again.

"What happened today is not seen in Israel - and I will make sure that it does not happen again. The entire government stands behind this decision," he said.

"The IDF will immediately use all its strength to destroy Hamas' capabilities. We will cripple them to the point of destruction and we will take revenge with might for this black day they have brought upon the State of Israel and its citizens," he added.

The IDF on Saturday said: "As families all over Israel are gathering around the dinner table, instead of eating dinner, they are once again forced to run to bomb shelters due to Hamas' incessant rocket fire."

At about 6:30 am (local time), a barrage of rocket fire began from Gaza into Israel, hitting several cities including Tel Aviv, Rehovot, Gedera and Ashkelon.

This was followed by several Hamas terrorists entering Israel from the Gaza Strip and taking over Israeli towns.

Hamas military commander Muhammad Al-Deif called the operation "Al-Aqsa Storm" and said that the assault on Israel was a response to attacks on women, the desecration of the al-Aqsa mosque in Jerusalem and the ongoing siege of Gaza, CNN reported.

Netanyahu said: "All the places where Hamas is organized, of this city of evil, all the places where Hamas hides, operates from - we will turn them into cities of ruins."

"I say to the residents of Gaza: get out of there now because we will act everywhere and with all the strength. At this time, IDF forces are clearing the last settlements of terrorists. They are going settlement by settlement, house by house and returning control to our hands," he said.

Some graphic videos showed bodies strewn in the streets of the southern city of Sderot after the attack by Palestinian militants. Cars were riddled with bullets and lit on fire, according to The Washington Post.

In a major development, the Israeli Mayor, and head of the Sha'ar Hanegev Regional Council, Ofir Liebstein, was also killed in the deadly rocket fire.

In response to the deadly attacks, the Israel Defense Forces also declared a 'readiness for war'.

Meanwhile, Ukraine's President Volodymyr Zelenskyy has said anyone who causes terror and death anywhere on the planet must be held accountable.

"We in Ukraine have a special feeling about what has happened. Thousands of rockets in the Israeli sky... People killed just on the streets... Civilian cars shot through... Detainees being humiliated..." Zelenskyy wrote on 'X'.

He said the attack on Israel was well-planned, and the entire world knows which sponsors of terrorism could have endorsed and enabled its organization.

"Israel has the full right to defend itself against terror. As any other state. And it's critical that the whole world responds to terror in a unified and principled manner," he said.

Australian Prime Minister Anthony Albanese also reacted to the Hamas attack on Israel, saying: "Australia stands with our friend Israel in this time. We condemn the indiscriminate and abhorrent attacks by Hamas on Israel, its cities and civilians. We recognise Israel's right to defend itself."