The insurgents came at midday, walking across a canal, advancing under cover of mortar fire toward the cluster of three Iraqi villages.
Within eight hours, Shiite residents who fled said the Sunni insurgents had expelled thousands of them from the majority-Sunni province, helped by local Sunnis in neighbouring villages.
"You cannot imagine what happened, only if you saw it could you believe it," said Hassan Ali, a 52-year-old farmer siting in the al-Zahra Shiite mosque, used to distribute aid in the northern Iraqi city of Kirkuk, where the displaced had fled, some 80 kilometres away.
"They hit us with mortars and mortars, and the families fled, and they kept hitting us. It was completely sectarian. The Shiites, out," he said.
The attacks took place on June 16 in the neighbouring villages of Chardaghli, Brawchi and Karanaz, as well as a fourth village, Beshir, some 50km to the north, said the displaced residents. All places were home to Shiite Turkmen, an ethnically distinct minority who speak their own language and are scattered through Iraq.
More than a dozen displaced residents in Kirkuk and the nearby Shiite Turkmen town of Taza Khormato gave The Associated Press near identical accounts of the expulsions. It was not possible, however, to independently confirm the incidents because Sunni insurgents now control of the villages.
The expulsions show how Iraq's sectarian mosaic is unravelling in particularly hateful ways, unseen since the mid-2000s when sectarian killings nearly plunged the country into civil war.
The difference this time around is the lack of a US military presence. At the time, when Iraq spiralled toward a sectarian civil war, US-led troops fought both Sunni and Shiite extremists, eventually brokering an uneasy peace until foreign troops withdrew in 2011.
The expulsions appeared to be part of a plan to create a Sunni-dominated territory from the Syrian border to Baghdad's edge.
The rough plan appears to have emerged after insurgents, led by fighters of the al Qaeda inspired Islamic State in Iraq and the Levant (ISIL), began sweeping through Iraq on June 9, seizing the country's second largest city of Mosul and heading southward into Iraq's Sunni heartland.
The three Turkmen Shiite villages were in Salahuddin, a central province that links the west to the capital.
Expulsions from those villages were preceded, just days earlier, by insurgents seizing the Turkmen-dominated city of Tal Afar near the Syrian border. There, they burnt down Shiite homes.
The Islamic State fighters consider Shiites to be heretics, and proudly post images of them being killed - often for no reason other than their beliefs.
But even less-ideological Sunni groups that are fighting alongside the extremists have grievances against Shiites, and see them as an obstacle to having a more autonomous territory.
They deeply resent the Shiite-dominated government of Prime Minister Nouri al-Maliki. The litany is long: harassment by security forces; lacking political representation, disenfranchisement, and neglect of Sunni provinces.
The first mortar shell to hit the three villages in Salahuddin exploded just after lunch on Monday (local time), the displaced said. Residents were worried: villagers had seen jeeps race into the Sunni village of Yenkeje across the canal.
Shiites watched from rooftops as insurgents poured out of their vehicles under cover fire and steadily advanced toward the village, the displaced residents said.
When villagers first fled toward the nearby Sunni villages of Bir Ahmad and Bastamli, they realised that insurgents were also firing mortars at them from that direction. Attempts to flee south to the Shiite village of Brawchi were in vain - it too was under attack. Rooftop snipers in the nearby Sunni village of Albu Hassan shot at them as they ran, they said.
Men, women and children were killed in the melee, three residents said.
"Among them was an old man and a woman, children, youths," said farmer Ali.
Days after they were killed, after pleading interventions to Sunni tribal leaders, the insurgents agreed to dump the bodies on a roadside for collection. The displaced residents say between 15 and 25 people were killed.
"They called and said: send somebody to collect your dogs," a 35-year-old villager, Abu Falah, said, lying in bed at the home of relatives in Kirkuk. A policeman, he was wounded in a recent suicide bombing, and his leg was reinforced with metal screws.
Farmer Ali said he helped bury the dead, which he said numbered 20, in a mass grave in the nearby town of Toz Khormato, controlled by Kurdish forces. It was where many displaced Shiites initially fled to on Monday night, before drifting to Kirkuk, also controlled by Kurdish forces, but considered safer.
On the same day the three villages came under attack, Sunni insurgents also attacked nearby Turkmen Shiite village of Beshir. Within hours, about 7000 people fled, under sniper fire as they passed neighbouring Sunni villages, displaced residents said. Kirkuk police chief Torhan Abdul-Rahim corroborated the story.
Residents from each village said that after they left, their Sunni neighbours burned down their homes, set fire to their wheat, and stole their sheep. They said insurgents also blew up some Shiite mosques. They said they knew of the looting because other Sunnis, opposed to the sectarian violence, were calling to update them.
One medical clinic manager from Beshir who requested anonymity, fearing his neighbours, said he had worked with residents of the nearby Sunni village of Muamaleh for years.
"If you serve somebody for 20 years, could you betray them? Let their bodies be eaten by dogs?" he grieved from a relative's small house in Kirkuk, where he now lives packed into a few rooms with five other families.
It wasn't immediately possible to contact people who had remained in the villages. Fleeing Shiites said they feared retribution if they provided telephone numbers. They also said they wanted to protect those still providing them with information.
Community leaders were trying to account for the thousands of displaced and some residents were presumed dead.
"Awn Qassim, my brother-in-law, he has seven children, nobody can find him," said Ayad Suleiman, 28, from Beshir. "Please tell the Red Cross," he asked.
Within days of the reported expulsions, more of the threads keeping Iraq together unravelled.
Abdul-Rahim, the Kirkuk police chief, said residents of three Sunni villages close to frontline combat fled into Sunni-majority areas, fearing retribution by Shiites.
Now, in Taza Khormato, only armed men remain defending the pastel-colored homes in the Turkmen Shiite town. The men evacuated their wives and children, fearing attacks.
In one house, men distributed shiny assault rifles and rocket-propelled grenade launchers. Gunmen patrol the town's entrance, emblazoned with a poster of an Iraqi soldier standing atop an insurgent's flag.
"We won't let anybody enter this village," said Yashar Hussein, 41, carrying two pistols. "Even if everybody dies."