[1] At around 6:30 AM, red alert sirens and the sounds of explosions from Iron Dome interceptors deployed in the area were heard.

[1] In the meantime, Eyal Rhein, the head of the security team, realized that the volume of rocket fire was out of the ordinary and went outside to investigate.

The militants damaged some equipment in the cowsheds and penetrated the area where foreign employees from Nepal and Thailand lived on the southern side of the kibbutz.

[1] Simultaneously, militants marauding near the kibbutz along Road 232 and in the surrounding fields killed civilians fleeing the Re'im music festival massacre.

A few civilians fleeing along the road attempted to seek shelter in the kibbutz only to be attacked by militants who had arrived from the back gate.

Yishai and Noam Slotki, two brothers from Beersheba who were IDF reservists, also joined the battle after arriving in the area by car, and fought the militants along the road near the entrance to Alumim before being killed at approximately 9:30 AM.

About 10 minutes later, two militants were killed near the front gate by security team members Eran Schlissel and Kobi Be'eri and the artillery officer.

The intruders were an Israeli couple, Ofek Atun and Tamar Kam, who had fled the Re'im music festival massacre and had broken into the house as they thought it had been abandoned.

Members of the security team as well as Ohad Braverman rushed to take positions blocking the militants' entry to the residences.

In the subsequent exchange of fire, two militants were killed, one of whom was found to be a commander in possession of documents describing the attack plans, and two security team members were wounded.

Between 9:30 and 9:45 AM, a Wolf Armoured Vehicle carrying Israel Border Police officers arrived and briefly assisted in transporting some of the defenders from the front gate to the place of fighting near the recreational area, taking heavy fire while doing so, before it left after being dispatched to Kfar Aza.

The situation for the defenders became increasingly desperate, with three wounded, much of their ammunition expended, and militants seen roaming freely around the perimeter fence.

However, seemingly deterred by the fierceness of the defense they encountered and the death of their commander, the militants abandoned their attack on the residences and began moving towards easier targets.

[2][4] At one point, a militant was spotted by security cameras in the kibbutz's vehicle repair garage trying to break into a car, and was subsequently confronted and wounded in the leg.

At another point, a member of the security team who had been wounded but continued fighting managed to shoot a militant near the perimeter fence some 200 meters away.

[1] At 11:00 AM, the first reinforcements from the Israel Defense Forces arrived when a CH-53 helicopter carrying soldiers of the 890th Battalion of the 35th Paratroopers Brigade landed near the kibbutz.

The helicopter had been hit by an RPG while descending and minutes after the troops disembarked, it was destroyed on the ground by another anti-tank missile.

At noon, 20 commandos from the elite Shaldag Unit of the Israeli Air Force arrived and for about 40 minutes engaged militants in the area between the road and the southeast corner of the kibbutz.

A reserve officer from another unit who had joined the Shaldag troops, Major Nimrod Palmach, subsequently brought the paratroopers into the battle for the kibbutz after they regrouped.

In addition, soldiers of the Yahalom special forces unit from the IDF Combat Engineering Corps arrived at the kibbutz with an armored vehicle to join the fighting.

[6][7] A few Israeli civilians who sought shelter in Alumim after fleeing the Re'im music festival massacre were killed in the kibbutz.

One survivor of the festival massacre, Ofek Atun of Holon, was killed after he and his girlfriend Tamar Kam broke into the home of an elderly couple that they thought was abandoned to take shelter.

They were IDF reservists who had come to the area on their own initiative after hearing of the attack to take part in the defense of Alumim without having been called up.

They were among the seven children of Rabbi Shmuel Slotki, who was called up to help identify bodies in the aftermath of the attack and carried on this work during the five days his sons were unaccounted for.

[15] A video, allegedly of a militant captured at Alumim, reportedly shows him pointing out further instructions to carry out beheadings, amputation of legs, and permission by his group leaders to rape the corpse of a girl, which would be war crimes.