Editor's note: This story contains graphic descriptions of violence.
KIBBUTZ BE'ERI, Israel — Who were the militants who swept in from Gaza to southern Israel on Oct. 7 and killed more than 1,400 men, women and children?
Some of them spray painted their names and the names of militias in blue, brown and green letters on the outside walls of a home they ravaged.
Some of them videotaped their brutality wearing body cameras.
Nearly 2,000 people attacked 29 different locations, including residential communities and army bases, Israel says.
Many of them returned to Gaza — estimated to have taken nearly 230 hostages back with them.
But hundreds of Hamas fighters were killed, and dozens were detained, by Israeli forces.
As Israeli bombardments on the Gaza Strip continue, which Gaza health officials say have claimed the lives of more than 7,000 Palestinians, new details are emerging about the men who carried out the brutal violence in Israel that sparked the current war.
They were young. They were well-trained. They had specific orders. They had a mix of motivations, tied to the unique conditions and ideologies that permeate life in Gaza.
And their mass killings, kidnappings and brutality have forever changed the lives of Israelis and Palestinians.
Word spread fast in one Gaza neighborhood
Among the throngs who crossed into Israel on Oct. 7 was a 25-year-old man named Mohammed.
In an interview with NPR, his neighbor in Gaza said Mohammed had led an ordinary life. He didn't finish his high school matriculation exam. He worked as a taxi driver, had a big wedding party with family and friends, and started a business selling food products.
Everyone in the family and neighborhood knew he belonged to the militant wing of Islamic Jihad, a smaller Palestinian militia in Gaza that is closely aligned with Iran.
Mohammed disappeared on the day of the attacks, his neighbor said. His family only discovered what happened the next day, when a fellow militant returned from Israel back to Gaza with Mohammed's cellphone and personal effects, and told Mohammed's family what had happened.
He said Mohammed had made it a mile or two inside Israel when an Israeli aircraft shot him — five bullets to the chest, one near the neck — and recited the shahada, Islam's affirmation of faith, before he died from his wounds.
"May God be merciful with him," his father told NPR. "To be a martyr is a huge thing, and this is what he pursued. I hope God accepts him as a martyr."
Both his neighbor and his father spoke on condition of anonymity, and referred to Mohammed only by his first name, out of concern Israel could target them.
What motivated the attackers
What motivated the attacks on Oct. 7 is a hotly debated topic.
A senior Hamas official told NPR the group staged the attack to draw attention to Israel's punishing restrictions on the Gaza Strip. Other Hamas leaders say they took hostages hoping for a grand prisoner exchange to free Palestinians in Israeli jails.
"We want to get the attention of the world," said Ghazi Hamad, a member of Hamas' political bureau. "Please, look at the Palestinians. We are under oppression and torture and collective punishment all the time. This is our message to the world."
Israeli officials say it's an ideology of hate against Jews and Israel that is dominant. Prime Minister Benjamin Netanyahu called Hamas "worse than ISIS." Israel, the United States and other countries recognize Hamas and the smaller Islamic Jihad group as terrorists.
Harel Chorev, a Palestinian affairs expert at the Moshe Dayan Center for Middle Eastern Studies at Tel Aviv University, says Hamas' goal is to break down Israeli society, which it sees as a colonialist people without real roots in the land.
"They always believe that all of us should go back to Germany and Poland and whatever, even if we are from Morocco," Chorev says. "It's really to break our spirit."
There is Gaza's history: Most Palestinians there descend from refugees uprooted from their homes in Israel's founding war 75 years ago. Failed rounds of Israeli-Palestinian peace talks have driven support for what Palestinians call armed resistance to Israeli occupation and brutality against the population.
There is Israel's strict policy toward Gaza, leading to a travel and economic blockade on the territory for the last 16 years. Israel says this is to contain attacks by Hamas after it took over Gaza in 2007 from the internationally recognized Palestinian Authority, now based solely in the occupied West Bank. Netanyahu's longtime policy was to preserve this political division between the territories to prevent them from uniting into one Palestinian state.
There is also the reality of daily life: Most in Gaza are poor, and most young people are without a job. Not every young Palestinian belongs to Hamas, but militant groups offer a steady salary, and shape a worldview, experts say.
"I'm not a radical Muslim, but [for] those who belong to Hamas, I think it becomes part of the socialization process, part of the education process ... hating the Jews or hating Israel as an occupier," says Palestinian political analyst Mkhaimar Abusada, who is in Gaza. "That probably explains the brutality that took place on the 7th of October."
There are around 20,000 to 25,000 militants in Hamas' Qassam militant wing, according to Gaza experts Samir Ghattas of the Cairo-based Middle East Forum for Strategic Studies and National Security, and Harel Chorev of Tel Aviv University. They estimate about 5,000 to 6,000 belong to Islamic Jihad's Al-Quds Brigades.
Taken together, it's a small share of Gaza's population of more than 2 million, but a significant force.
The worst of the brutality
In the Kibbutz Be'eri massacre, spacious homes were torn apart: kitchens turned upside down; Rummikub game tiles and an elderly man's walker strewn over the floors. In one house the smell of a blood-soaked mattress lingers.
Israel's army says it collected terabytes of footage of the attacks from GoPro cameras retrieved from Gaza militants, as well as victims' cellphones and neighborhood security cameras.
The military posted some of the raw footage online, and showed 43 minutes of some of the more explicit videos to foreign media, including NPR.
The videos show both methodical and erratic behavior.
At Be'eri, gunmen waited for a car to approach and open the kibbutz's main gate, before shooting the driver and infiltrating the community.
The videos also capture the men's heavy breathing, nervous pacing and shouted instructions. In one of the most gruesome scenes screened to foreign media, a man calls out for a knife and calls to cut off a wounded man's head, before attempting to behead him with a garden hoe.
The military says some of the perpetrators were found to be under the influence of narcotics.
Human Rights Watch said it verified four videos of attacks by Hamas-led gunmen and called for the attacks to be investigated as war crimes.
Advanced training for elite combatants
Ghattas, the Gaza expert in Cairo, believes elite combatants in Gaza traveled on false passports to countries like Lebanon or Iran where they learned the combat methods of the Iran-backed militia Hezbollah. He believes they returned to Gaza to train the squads who carried out the attacks.
The Israeli army wouldn't elaborate on the question of foreign training, but asserts there was Iranian involvement. Iran denies there was prior coordination.
Israel has released images of pamphlets the military says it found with the Hamas fighters — containing detailed attack and abduction plans — and has released interrogation videos of several of the attackers it has detained.
In the videos, the men claim their orders were to kill, and to take many hostages back to Gaza. One claimed those who took hostages were promised $10,000 and an apartment.
A call from a proud son
The Israeli military released a recording it says was a phone call — placed during the attack — from one of the attackers to his family back in Gaza.
"Your son killed Jews," the voice says. "Ten with my own hands, mom!"
"Oh my son, may God protect you," a woman's voice answers in tears.
"Enough. Come back, come back," a man's voice says.
"What do you mean come back?" the son says. "There is no coming back. It's either martyrdom or victory."
Was the son killed or detained in Israel? Did he return to his family in Gaza? Israel's military declined comment.
What we know is that his family, like every other family in Gaza and Israel, now faces the consequences of yet another war.
