When demonstrators took to the streets of Baghdad in early October, two military medics, Abbas and Ahmad, saw people beaten back by police and soldiers, cut down with canisters and bullets and overcome by noxious gases designed for use on the battlefield.

Later in the month they left their homes, ignored their orders and joined the demonstrators in the heart of the Iraqi capital, and they have been treating those wounded in the clashes ever since. “We couldn’t just stay at home and pretend nothing was happening,” said Ahmad. “We had to get out and look after the injured.”

Baghdad is familiar with war and insurgency but far less so with protests led by unarmed citizens demanding a change to the terms of the contract between citizen and state.

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In unprecedented daily demonstrations, up to 200,000 protesters at a time have called on Iraq’s leadership to hand over power to officials who would end the structural corruption and patronage networks that have whittled away the country’s vast oil wealth.

At the same time, they have demanded that Iran’s extensive role in Iraqi affairs be pared back. Neither Iraqi officials nor their overlords in Iran appear inclined to compromise. Instead, a tolerance of the protests over the first fortnight has given way to a violent crackdown. More than 300 people have been killed and thousands more injured, many in Tahrir Square in central Baghdad, the heart of the movement.

It is here that Ahmad, 31, and Abbas, 32, have been treating people, and here that the the crackdown on demonstrators has become an open war on medics.

The two men honed their skills in trauma medicine while fighting Islamic State in the ruins of Mosul, Tikrit and Baiji. “After the war against Isis, I didn’t think I’d see battles this intense again,” said Abbas. “But the streets and squares of Baghdad have turned out worse. In war, casualties were something to be expected. In the past weeks in the protests, I’ve seen some serious injuries that I rarely came across in battle.”

Facebook Twitter Pinterest An injured protester is helped into a tuk-tuk. Photograph: Ghaith Abdul-Ahad/The Guardian

The casualties arrive sometimes in tuk-tuks used as makeshift ambulances or carried by frantic protesters using the flags they had been waving to staunch gunshot wounds.

The shock of treating dying civilians who moments earlier were members of an empowered civic movement is something that neither man has come to terms with. They struggle to make sense of the contrast between the electrifying energy of street power and citizenship, and the familiar thrum of the brutal crackdown.

“Even Isis wouldn’t shoot at medical staff during the worst of the fighting,” said Abbas. “But the riot police are sniping at civilians with smoke and teargas grenades.”

Dozens of severely injured protesters have been brought to them with canisters fizzing gases embedded in their bodies. These are small containers of military-grade teargas, typically lobbed on to a battlefield but in this case fired directly as projectiles.

“Some injuries are the kind I never saw before,” said Abbas. “The canisters penetrate heads and body parts, causing gruesome wounds, and it is tough to deal with.”

Facebook Twitter Pinterest A teargas canister is fired into a group of protesters in Baghdad. Photograph: Thaier al-Sudani/Reuters

Ahmad has also been hit by a canister, which luckily failed to penetrate his skin, as well as by numerous rubber bullets. He unwrapped his left arm to show a wound from a gas can. His back was peppered with bruises. “I was shouting that I’m a medic, but the police didn’t stop firing at me,” he said.

Four more people were killed in Baghdad overnight and into Thursday as security forces shot live fire and teargas canisters at protesters near two key bridges.

Human Rights Watch said the extent of the attacks on medics “show an utter disregard for the overriding need to ensure medical workers can do their essential job”.

Facebook Twitter Pinterest A protester holds a teargas canister fired by police. Photograph: Ahmed Jalil/EPA

Amnesty International said the teargas canisters being used were either Serbian- or Iranian-made and between five and 10 times heavier than containers typically used by riot police for crowd control measures.

Other medics have also been targeted. Khalil, 22, who like his colleagues did not disclose his surname, was wearing a flak jacket beneath his white coat, which had a large hole in the back. “The riot police fired a smoke grenade at my back when I tried to help a protester who had been shot,” he said. “I was lucky that I had the body armour on otherwise it would have caused a fatal injury.”

Some medics have been arrested and not heard from since. Others have been told they are wanted by the police. “A medical student who worked with us on the Sinak bridge was taken into custody on his way back home,” said Khalil. “And we haven’t heard from him since then.”

Abbas and Ahmad know what awaits them if the government prevails. “National security service officers visited my house and told my family that I need to visit them and they have an arrest warrant for me,” said Abbas. “I was told by colleagues that I’ve been suspended from the army and I would need to face military trial, but I don’t care. If they want me they can come and get here.”

Ahmad was just as sanguine. “I got a call from an unknown number yesterday telling me to take care of myself because people are looking for my head,” he said.

Facebook Twitter Pinterest A protester skips past burning fires in Baghdad. Photograph: Ghaith Abdul-Ahad/The Guardian

Across Baghdad, the numbers of people being quietly picked off the streets is rising and there are growing fears among demonstrators of what is to come if their calls for change fail.

A lawyer for one of the disappeared said: “My client was picked up by a masked group who called themselves intelligence officers on his way back from Tahrir Square. He was beaten very badly and now he is facing charges for inciting violence.”

Speaking in a low voice in a Baghdad coffee shop, he continued: “My client is held in a crowded cell in a terrible condition. The courts are not functioning, so I can’t get him out. Torture and verbal humiliation have become a norm against the peaceful protesters.”

While aware of the disappearances, many in Baghdad believe momentum remains on their side and are willing to make open contributions to sustain the protest movement.

Ismail, a 45-year-old pharmacy worker, was delivering medicines and drugs to the medical teams daily, either for free or at steep discounts. “If we didn’t provide the medics with basic needs, thousands would have lost their lives,” he said. “We are only doing our share for the youth who are unfairly getting hurt in the hundreds every day.”