It’s been three months since the devastating Hamas attack that sparked Israel’s war in Gaza, and the deadly fighting has led to a dire humanitarian crisis in the area. 

The Israeli military began an offensive on the Palestinian enclave after Hamas militants launched a brutal assault on Israel on October 7, with gunmen killing around 1,200 people and taking more than 200 people hostage, according to Israeli authorities.

In the three months since the attack, more than 22,700 Gazans have been killed, according to the Hamas-run health ministry.

Here’s a look at some of the key moments in the conflict:

October 7: Hamas’ attack. Hamas’ surprise October 7 assault marked the biggest terrorist attack in Israel’s history. At least 1,500 Hamas fighters poured across the border into Israel by land, sea and air using paragliders. Soon after, Prime Minister Benjamin Netanyahu said Israel was “at war.”

October 9: Israel orders the “complete siege” of Gaza. Two days afterwards, Netanyahu said the Israeli military would attack Hamas with a force “like never before,” with the goal of destroying the militant group.

October 13: A growing exodus. Israel’s military told 1.1 million people in northern Gaza to evacuate their homes immediately, as it stepped up its response. Since the conflict began, the UN estimates up to 1.9 million people have been displaced.

October 17: Hundreds killed at Gaza hospital. A deadly blast tore through Al-Ahli Baptist Hospital in Gaza, which was sheltering thousands of displaced people. CNN found that the blast was likely caused by a malfunctioning rocket fired by Palestinian militants rather than an Israeli strike.

October 27: Israel expands its ground offensive. After a war largely conducted from the air, the Israel Defense Forces announced it was “expanding ground operations” in Gaza.

November 15: Al-Shifa hospital raid. Israel launched a “targeted” operation against Hamas inside Gaza’s largest hospital, where thousands of Palestinians were believed to be sheltering. Conditions at the hospital deteriorated rapidly in the days of fighting. The raid sparked international criticism.

November 24: A truce begins. After days of careful negotiations, a truce between Israel and Hamas brought a pause to fighting. As part of the truce, civilian hostages held captive by militants were released, with groups of hostages being released each day.

December 1: The truce collapses. One week later, the Israeli military resumed fighting against Hamas in Gaza, accusing the group of breaking the terms of the truce. Israel’s focus began shifting from northern to southern Gaza.

December 15: Hostages killed in botched raid. Israeli soldiers shot and killed three Israeli hostages in northern Gaza after misidentifying them as threats. The IDF said the shooting was against its rules of engagement and that the soldiers involved would face disciplinary procedures.

January 1: Israel announces partial withdrawal. On the first day of the new year, Israel announced it would soon begin pulling thousands of soldiers out of Gaza in preparation for a new phase of the conflict, although a top official warned that he expected the fighting to continue throughout the year.

Read more: Israel is shifting to a new phase of its war on Hamas.