Information from the United Nations website (https://www.un.org/en/situation-in-occupied-palestine-and-israel) accessed 15 Nov 2023:

On 7 October 2023, Palestinian armed groups in Gaza launched thousands of rockets toward Israel and breached through the perimeter fence of Gaza at multiple locations, entering into Israeli towns and killing and capturing Israeli forces and civilians. The Israeli military declared “a state of war alert,” and began striking targets in the Gaza Strip, including residential buildings and health care facilities. Since then, thousands of people have been killed and more than one million have been displaced, as parts of Gaza have been reduced to rubble.