Videos posted on social media showed what appeared to be uniformed Palestinian gunmen inside the Israeli border town of Sderot.
A video from Gaza showed what looked like the lifeless body of an Israeli soldier being trampled by an angry crowd shouting “God is Great,” AP reported. Another video appeared to show Hamas terrorists dragging away a live Israeli soldier on a motorcycle, the news agency said.
Other videos showed a crowd of Palestinian men dancing around and atop an Israeli tank that was burning. Footage also emerged allegedly showing an Israeli mother and her children being kidnapped.
The IDF said it had responded with air strikes into Gaza, where witnesses reported hearing heavy explosions.
The Israeli Prime Minister said in a speech: "Citizens of Israel, we are at war, not in an operation or in rounds, but at war. This morning, Hamas launched a murderous surprise attack against the State of Israel and its citizens. We have been in this since the early morning hours.
Benjamin Netanyahu addresses the nation (Photo: Israel PM Office)
"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 mobilisation 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."
Netanyahu also convened a security meeting at the Kirya military headquarters in Tel Aviv attended by defence minister Yoav Gallant and other high-ranking officials.
The IDF was ordered to a “state of war readiness” and Gallant authorised the call-up of reserve troops.
He also announced a "special security situation" within 80 kilometres of the Gaza Strip, enabling the IDF to close relevant sites and impose safety restrictions on the population.
The IDF later announced the launch of an operation named "Iron Swords."
“The Hamas [terrorist organisation] has made a grave mistake this morning and launched a war against the State of Israel. IDF troops are fighting against the enemy at every location," said Gallant.
"I call on all of Israel’s citizens to follow security instructions. The State of Israel will win this war," he added.
Hamas said it had launched 5,000 rockets at Israel in an early morning surprise attack it calls “Operation Al-Aqsa Flood.”
IDF spokesman Lt Col Richard Hecht said in a briefing that Israeli forces “are fighting on the ground as we speak,” listing at least half a dozen locations where fighting is taking place, including several villages, two army bases and border crossings.
UK Prime Minister Rishi Sunak said he was "shocked" by the attacks. "Israel has an absolute right to defend itself. We're in contact with Israeli authorities, and British nationals in Israel should follow travel advice," he added on X/Twitter.
Labour leader Sir Keir Starmer said: "I utterly condemn the ongoing attacks on Israel and her citizens.
"There is no justification for this act of terror which is being perpetrated by those who seek to undermine any chance for future peace in the region. Israel has a right to defend herself."
The scene where a rocket fired from Gaza into Southern Israel, hit and caused damaged in the southern Israeli city of Ashkelon (Photo: Flash 90)
Mohammad Deif, the Hamas military commander, issued a statement saying that the ongoing attacks are in retaliation for Israel’s “desecration” of the Al-Aqsa Mosque in Jerusalem.
He added that Israel killed and wounded hundreds of Palestinians this year, and that Israel rejected offers for prisoner exchange deals.
At least 198 people in the Gaza Strip have been killed in Israel's retaliation and at least 1,610 wounded, the Palestinian Health Ministry in Gaza said.
