Mohammed Abdulrazzaq was gathering water in Mosul when shrapnel tore into his legs, making him one of a growing number of wounded from the battleground Iraqi city putting huge strains on hospitals.

Iraqi forces launched a massive operation on October 17 to recapture Mosul, the country's last city held by the Islamic State group, and while they have advanced into its east, large parts remain under jihadist control.

Abdulrazzaq said his arms were loaded with jerry cans of water when the shellfire struck with "a huge boom" that left him deaf in one ear.

He then "saw the blood squirt" from his legs.

His legs covered in bandages, Abdulrazzaq is now hospitalised in Arbil, the capital of Iraq's autonomous Kurdish region that is located around 100 kilometres (60 miles) east of Mosul.

"There, it is a terrible street war," said the bearded 43-year-old.

At the hospital, "every day, I see dozens of wounded arrive. We are already being crammed in and there will be many more," he said.

- 'They are not humans' -

His wife, five children and 80-year-old mother are still in Mosul, where IS chief Abu Bakr al-Baghdadi announced the group's cross-border "caliphate" in 2014.

Saddam Georgis, who was also wounded by shelling in Mosul, lived for two weeks in an area "liberated" from IS's brutal rule.

Like others he welcomed the arrival of Iraqi forces in the city's Al-Alam district.

But while the jihadists had been pushed out of the area, it was still within range of their mortar rounds.

"They are not humans, not Muslims, they strike civilians, aim at houses," the 45-year-old said from intensive care.

Georgis remembers the sound of the explosion and the shock of the shrapnel -- "like a stone that hit me in the thigh" -- the spurting blood, being transported on a makeshift cart.

After that, he recalls nothing until he woke up in hospital.

"I don't even know if my four children were able to reach relatives in Mosul," he said, his wife sitting at his bedside.

Zainab, a 10-year-old girl, was also hit in the legs by shrapnel, as was her two-and-a-half-year-old sister.

"Our neighbourhood has been liberated but the firing continues," their mother said.

- Looming 'disaster' -

Human Rights Watch has said that IS is "indiscriminately" attacking Mosul residents who refused to retreat when it did, and that Iraqi and US-led coalition forces are also putting civilians in danger.

"Residents said (IS) members told them in person, by radio, and over mosque loudspeakers that those who stayed behind were 'unbelievers' and therefore valid targets along with the Iraqi and coalition forces," the rights group said.

The hospital where Zainab, her sister and the two men are being treated is facing a wave of patients, said Rauf Karim, its head nurse.

"Some days we receive 25 new patients, others more than 30," including children, Karim said.

The growing number of wounded adds to "several crises" already burdening the medical sector in Kurdistan, said Saman Barzanji, the head of the Arbil health department.

It has already had to contend with the arrival of large numbers of people displaced by the war with IS as well as wounded members of the Kurdish security forces, all while the region faces major economic challenges.

"Our operating rooms are facing severe shortages of instruments and equipment," he said, adding: "This is a crisis and soon we could have a disaster."

"How long can we hold on?"