By Martin Asser
BBC News website correspondent in Jerusalem
Asher Weisgan had known two of those he killed for years
The place where the Tawafsha brothers died after a day's work at the Shilo Jewish settlement bears witness to the settlers' futile efforts to save
Used medical equipment lies on the ground amid still-sticky bloodstains near the settlement gate - sterile gloves, scalpels and needles.
There is also the affecting sight of what they were carrying when they lost their lives, a half-smoked pack of cigarettes, a shopping bag of Arabic bread.
Bassam and Usama Tawafsha were shot in cold blood by a Jewish settler whom they had known for many years, even shared food with. He was giving them a lift home, as he did every day.
Two other Palestinians died during Asher Weisgan's shooting spree in the settlement's industrial zone, and another was wounded, before settlement security guards overpowered him.
Mark, a security officer who prefers not to give his surname, prevents our entry into the settlement, saying they are on full alert in case Palestinians take revenge for the killings.
"I hope that the people around us realise that this is the act of a madman, that it does not reflect Shilo or Shuvat Rachel" (where Asher Weisgan lived), Mark says.
"All of our people are incredibly shocked - blown away - by what happened yesterday... These were guys who I knew, who I liked. I considered them my friends."
He adds that Shilo's residents were surprised by Weisgan's transformation into a killer - he was a "liberal" settler who did not "harbour any hatred" for Arabs.
"I think his mind just snapped, because of the history of violence in the area and because of what they presently call the disengagement," Mark says, referring to Israel's unilateral pull-out from Gaza and four West Bank settlements.
It's unusual to find concord between Jewish settlers living on occupied Palestinian land and Palestinians who live nearby - but in the village of Sanjal where the brothers lived a similar picture of Asher Weisgan emerges.
The vine-covered veranda of the Tawafsha family home is packed with female relatives, the men milling around in the street or sitting in reception rooms.
The men's mother begs for the return of their bodies, which have not yet been released by the Israeli authorities.
Usama's wife Aisha, her shocked children huddled around her, calls down revenge on Israel, the settlers and Prime Minister Ariel Sharon.
"When one of them kills us they say he is crazy, but if an Arab did that to a settler the whole world is up in arms saying he's a terrorist," Aisha says through her weeping.
"They worked with him (Weisgan) for eight years," she continues.
"They used to say how decent he was, how they used to eat together, how he used to ask them for our food to take to his wife," she says.
"Asher? He was very respectable," says neighbour Ataf Radi, one of a handful of Palestinians who worked at Shilo, but who luckily had not been at work the previous day.
"Our relationship with him was far better than you could imagine. No one could have expected this."
Among the other mourners on the steep hillside of Sanjal, from where the neat red roofs and elaborate synagogue of Shilo are clearly visible, there is equanimity about the threat they might face from militant settlers in the area.
"It could happen anytime," says Ziyad Sabri.
"Sometimes they come in the night and attack our homes. You are ready for them, you are not armed like them, but you always have a rock or a stick handy."
So what was behind Asher Weisgan's actions?
The killings have been condemned by Palestinians and Israelis
Why did he calmly get out of his car, apparently take a security guard's gun, open fire on his passengers, who considered him a friend, before heading back to the factory and gun down another Arab colleague?
Speaking to reporters at his court hearing the day after the killings, he said he wanted to stop the pullout from Gaza, which was in full swing as he spoke.
"I am not sorry for what I have done... and I hope someone murders Sharon as well," he said.
The Shilo/Shuvat Rachel enclave is isolated in the middle of a sea of Palestinian population and, though the settlers deny it, it is an obvious candidate for future evacuation.
His actions have been condemned unconditionally by settler spokesmen - as well as by the Palestinian and Israeli leaderships, who had also condemned the actions of another Israeli settler, Eden Nathan Zaada, who murdered four Israeli Arabs on a Galilee bus less than two weeks earlier.
So far these are two isolated incidents - albeit the worst violence so far associated with the evacuation of Gaza, in which the struggle between Jews and Jews has been conducted without violence on both sides.
But veteran Haaretz analyst Zeev Schiff called Weisgan and Zaada examples of the "wild grapes produced by Israel's extreme right" of whom "there are many" living in Israel's West Bank settlements.
Other examples are the killer of Prime Minister Yitzhak Rabin, Ygal Amir, and Hebron massacre perpetrator Baruch Goldstein.
Palestinian militant reaction has so far been muted to the latest provocations, but if any other "wild grapes" ripen during the disengagement, their retaliation could indeed bring about the desired disruption of the withdrawals.