“Citizens of Israel, we are at war. Not an operation, not a round [of fighting,] at war! This morning Hamas initiated a murderous surprise attack against the state of Israel and its citizens,” Netanyahu said in his filmed statement in Hebrew as quoted by The Times Israel.

According to reports, Hamas group members fired thousands of rockets into Israel and gunmen crossed the border with the Gaza Strip and invaded multiple Israeli towns, triggering tension in the region.

“We have been in this since the early morning hours. I have convened the heads of the defence establishment. I’ve given directives to clear the [affected] urban areas of the terrorists who penetrated them,” Netanyahu said. “This is happening right now.”

“In parallel, I am initiating an extensive mobilization of the reserves to fight back on a scale and intensity that the enemy has so far not experienced. The enemy will pay an unprecedented price,” Netanyahu said.

In his message to citizens, he said: "I urge the public to follow strictly the directives of the military, the Home Front Command. We are at war and will win."

Defence Minister Yoav Gallant said Hamas committed a 'mistake' by attacking Israel.

“The State of Israel will win this war,” he was quoted as saying by The Times of Israel.

Hamas is a Palestinian Sunni-Islamic fundamentalist, militant, and nationalist organization.

It has a social service wing, Dawah, and a military wing, the Izz ad-Din al-Qassam Brigades.

It won the 2006 Palestinian legislative election and became the de facto governing authority of the Gaza Strip following the 2007 Battle of Gaza.

It also holds a majority in the parliament of the Palestinian National Authority.