Hiding under corpses: Iraqi tribesmen recount escape from Islamic State Muhammed Hilal and about 100 other members of Iraq's Albu Nimr tribe felt safe hiding from Islamic State militants in tall grass -- until the headlights of dozens of cars exposed them. "We know you are there, traitors," militants shouted, before opening fire on the tribesmen who had fought them for weeks. Most died. Some were taken prisoner. Shot in the arm and leg, Hilal survived, after smothering himself in blood and playing dead under corpses as the militants beat the wounded and called them "scum," he said. Hilal says he spotted more bodies, including children and the elderly, dumped on the roadside as he fled the scene after hours of hiding beneath the dead. I'm waiting for my family. I have no way of reaching them. Their cellphones are switched off and I'm powerless to do anything," Hilal told Reuters by telephone from Haditha, a town under the control of Iraqi forces and tribal fighters but still vulnerable to attack from nearby Islamic State militants. Many other members of the tribe face that same uncertainty after Islamic State executed hundreds to punish the tribe that had fought back. After seizing the tribe's main village, Islamic State militants combed the area for those who had set out on foot hoping to escape the wrath of a group notorious for beheading or shooting dead anyone opposed to their ultra-hardline ideology. The killings raised new concerns about Iraq's ability to defeat Islamic State, which swept through northern Iraq in June, meeting little resistance from the U.S.-trained army. The Shi'ite-led government of Prime Minister Haider al-Abadi wants Sunni tribes like Albu Nimr, which once helped the United States defeat al Qaeda in Anbar, to back government forces fighting Islamic State. But tribal leaders say the government ignored repeated pleas for help as Islamic State pushed through Anbar, a vast desert province that includes the Sunni tribe-dominated towns in the Euphrates River valley running from the Syrian border to the western outskirts of Baghdad. Islamic State was on the march in Anbar even before it seized much of northern Iraq, coming ever closer to Baghdad as part of its ambition to redraw the map of the Middle East. It is now encircling the province's largest air base, Ain al-Asad, and the vital Haditha dam on the Euphrates. The carnage appears to have been carefully planned. Before Islamic State took the village of Zauiyat Albu Nimr, the insurgents planted informants who eventually handed over the names of fighters, tribal members said. On the night that they entered the village, the army retreated from the front line and they were evacuated. This left us with no ammunition and only fighters from the villages so we had to surrender," said shopowner Haji Rudaif. He, like many villagers, escaped with just the clothes on their backs. Some took the highway to the town of Hit, making the fatal mistake of believing promises of safe havens made by Islamic State. That is where the bloodletting began with 35 executions. Others, like tribal fighter Abu Ibtisam, 50, walked for about 6 km (4 miles) to a desert area west of Hit after militants took their gold and cash, ripping the jewelry off his daughter's neck. At an Islamic State checkpoint, one militant took powdered milk from his wife and tossed it in the dirt -- she frantically tried to collect it but was pushed back, he said. After robbing them they let them go free. "One of them said that even our children don't deserve to live because they will grow up one day and fight them back," said Abu Ibtisam. Like other tribesmen, he doubts an alliance with the government can be built. "The government paid no attention to us no matter what happened, if we knew that things would have turned this way then I wouldn't have fought," said Abu Ibtisam. I would have left the village with my family and my money, gold and dignity and not suffered these hardships. I regret having fought against Islamic State because I have gained nothing. The accounts could not be independently confirmed. Islamic State tactics are clear -- take over territory, eliminated anyone who stands in the way and try to run the area like a state. It has declared a caliphate in parts of Iraq and Syria. After members of the tribe scattered, tribal fighter Majid Ouda and two cousins headed for the desert where they hid for five days, surviving on dates and dirty water from a lake. Whenever cellphone coverage was available, he called his mother. One day she was frantic. His 13-year-old brother Mohammed was taken away along with others by Islamic State. "I told my mother not to worry since he's practically a child and he didn't even participate in the fighting," said Ouda. My family called me a day later when I reached the an army emplacement and told me that my brother and 47 more students were killed in the roundabout of Hit. They killed him because I'm a policeman. The Albu Nimr were seen as some of the fiercest fighters in Iraq, not just Anbar. During the U.S. occupation after the fall of Saddam Hussein in 2003, they took on Islamic State's predecessor in Iraq, al Qaeda, which specialized mostly in hit and run attacks and suicide bombings. Equipped with more funds and weapons seized from defeated Iraqi troops, Islamic State will almost certainly keep inflicting more punishment on any tribes that challenge them. The Albu Nimr are still counting their casualties. Hamdan al-Nimrawy, aide to one of the tribe's leaders, said the death toll has reached 540 with many people still missing. The grueling journey to escape was too much for some. Abu Takaa and his family of seven slept behind a sand dune in the desert to avoid detection. His wife became so dehydrated that she could no longer breast-feed her infant, he said. My youngest passed away. But his mother kept holding on to him and would not let go even after two days," he said. There was no time to mourn, fearing that Islamic State was on their trail. We buried the child there and we entrusted nomads with his grave and moved on.