CAIRO -- Accounts from witnesses and survivors cast doubt on American suggestions that the Islamic State of Iraq and Syria (ISIS) was to blame for the deaths of more than 100 people taking refuge in a house hit by a U.S. airstrike earlier this year in Mosul, the deadliest single incident of the months-long campaign to retake the Iraqi city.

U.S. officials said soon after the March 17 strike that investigations could find that militants forced people into the building, booby-trapped it with explosives, then lured in the strike.

None of that happened, according to seven witnesses and survivors who spoke to The Associated Press.

Instead, they described a horrifying battlefield where airstrikes and artillery pound neighborhoods relentlessly, trying to root out ISIS militants, leveling hundreds of buildings, many with civilians inside, despite the constant flight of surveillance drones overhead. Displaced families scurry from house to house, most of them driven out of their homes in other neighborhoods by ISIS militants, who herd residents at gunpoint out of districts about to fall to Iraqi forces and push them into ISIS-held areas.

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Their accounts underscore how increased use of bombardment has made the fight for Mosul's western sector, which began in mid-February, dramatically more destructive than its eastern half.

More than 1,590 residential buildings have been destroyed in western Mosul, based on analysis of satellite imagery and information from local researchers, the U.N. said last week. Airstrikes killed 1,117 people in western Mosul in March and April alone, according to Iraq Body Count, an independent group that documents casualties in the war, cross-checking media reports with information from hospitals, officials and other sources.

In comparison, an estimated 1,600 civilians were killed or wounded from all causes during the 100-day campaign to recapture Mosul's less densely populated eastern half, which ended in mid-January. Official figures from the Pentagon, which is slower in confirming deaths, are far lower: it said over the weekend that it has confirmed that coalition airstrikes killed at least 352 civilians in Iraq and Syria combined since the campaign against IS started in 2014.

The witnesses all told the AP that no one was forced into the building that was destroyed on March 17. It was seen as safe because it was not on a main road and was only two stories tall, making it unlikely to be used by ISIS militants as a sniper's position that might be hit by an airstrike. Its owner, Tayseer Abu Tawfiq, was a respected local businessman who let anyone in need stay with his own family of 14.

U.S. Central Command has refused to comment on the strike until its investigation is completed. An Iraqi security official said coalition aircraft were called in when ISIS fighters were seen moving house to house along rooftops, firing at Iraqi forces. Militants were also in the streets nearby, said the official, who spoke on condition of anonymity to discuss operational details.

Ali Zanoun, one of the only survivors of a U.S. strike on a building in Mosul, lies on his bed as he waits for another surgery at a hospital in Irbil, Iraq, in this photo from April 8, 2017. AP

Ali Zanoun was one of only two people in the house to survive the airstrike. Trapped in the rubble for five days, he drank from a bottle of nose drops, his only source of water.

Buried around him were the bodies of more than 20 family members, including his two wives, Luma and Nadia, three sons and four daughters, one of whom gave birth only two days earlier to an infant, who also died.

He and his family ended up in the house after ISIS militants drove them out of their homes in the nearby Ammel district before it fell to Iraqi troops. For a week, they bounced from house to house.

Finally Zanoun and one of his brothers ended up at Abu Tawfiq's house, because they heard he was "a humane person," the 50-year-old said from his hospital bed in the northern Iraqi city of Irbil.

It was small, only 2,200 square feet. The women crowded into the basement, while the men stayed in the two floors above.

Zanoun said he saw ISIS fighters in the streets in the days before the airstrike, and one day he saw a sniper on a roof about 300 yards away. But when asked if fighters ever entered Abu Tawfiq's house or used it to fire from, he said: "Never."

Another man, who gave only his first name, Khaled, to protect relatives still living in ISIS-held areas, ended up at the house after ISIS militants forced him out of his home at gunpoint. He stayed there for two days but left on the afternoon of March 16 because it was too crowded -- around a dozen families "and more coming," he said. His brother remained at the house along with his 12-member family.

He angrily dismissed the idea that ISIS booby-trapped the house. "Liars! Is it logical that I would stay in a house with explosives?" he asked. "Daesh didn't enter the house," he said, using an Arabic acronym for ISIS.

Abdullah Khalil Ibrahim, whose house is next door and was severely damaged in the strike, spoke to Abu Tawfiq the night before. There were no militants in his neighbor's home, Ibrahim said, adding that he told Abu Tawfiq it wasn't safe having so many people in one place. "I can't turn people away," Abu Tawfiq replied.

The next morning, the strike hit as Ibrahim and his wife were about to have breakfast. He heard a jet flying low, then the walls and ceiling collapsed from the impact. Under the wreckage, he hugged his 2-year-old son close as a fire raged.

Ibrahim survived along with his wife and son, though Ibrahim's leg had to be amputated. A five-member family staying at their home was killed.

During his days under that rubble, Zanoun said he heard people and fighters outside, along with the sound of gunbattles and more airstrikes. He would call for help, and sometimes someone would shout that they would bring water, but no one ever did.

Finally, his brothers dug him out. He was rushed to Irbil and underwent multiple surgeries. It was only later that they told him about his family. He began to scream his children's names.

"My entire family is gone," Zanoun said. "They melted. Not even a fingernail or a little bone found."