He lay in a bloodied ball on the floor, but the baton blows kept on coming. As the 30 strangers beat him without stopping, Mohammad Zubair closed his eyes, brought his forehead to the ground and prayed.

“The blows kept raining on my head, hands and back,” said Zubair, 37. “I did not ask them to stop beating me. I became silent, tried to hold my breath and stiffen my body.”

As he spoke, tears rolled down his face. “First I asked, ‘Why are you attacking me? What wrong have I done?’ But they did not listen to my words and went on hitting me from all sides. They were shouting maro shaale mulleko [kill the bastard Muslim] and jai Sri Ram [a Hindu nationalist slogan]. There were many other men who stood by who did not come to save me.” The photo of Zubair being ruthlessly beaten in broad daylight in the streets of Delhi by a mob of young Hindu men was one of the most shocking images of the brutal religious riots that engulfed Delhi, where Hindus were pitted against Muslims, thousands were injured and 43 people killed.

Facebook Twitter Pinterest Mohammad Zubair, 37, is beaten by a Hindu mob in one of the most shocking images from a week of violence in Delhi. Photograph: Danish Siddiqui/Reuters

The violence raged across the north-east of India’s capital for four days as mosques were set alight, Muslims were burned alive in their homes or dragged out into the streets and lynched. Muslim businesses and property were also set alight. In streets where Hindus and Muslims had lived peacefully side by side, bodies lay bloodied alongside discarded and burned-out cars, bikes, shattered glass and smouldering shopfronts. The police have been accused of enabling, encouraging or even joining in with Hindu mobs.

Hindu mobs were stopping men in the streets demanding to see their ID cards. If anyone refused, they were forced to show whether or not they were circumcised, as is common among Muslim men. Imran Khan, 30, a street hawker who lives in Shiv Vihar, north-east Delhi, was walking home on Monday evening when a group descended on him.

“Some of them forced me to pull down my trousers,” he said. “They started beating me violently as soon as they became sure that I was Muslim.”

Armed with iron rods, crowbars and metal pipes, the Hindu mob beat Khan unconscious. When he came to hours later, he found that the attackers, assuming he was dead, had tied a rope around his neck and dragged him into a gutter.

Facebook Twitter Pinterest ‘They saw I was a Muslim and just started attacking. What kind of humanity is this?’ Mohammad Zubair after being beaten by a group of men chanting pro-Hindu slogans. Photograph: Danish Siddiqui/Reuters

There has been brutality on both sides, but it was the Muslim community of Delhi who were overwhelmingly targeted by Hindu mobs in their tens of thousands. In Chand Bagh, one of the worst hit areas, only the Muslim businesses – hairdressers, ice-cream shops, butchers – lay in ruins. On one corner, the charred husks of hundreds of oranges, bananas and watermelons spilled out of the front of a Muslim fruit stall, filling the air with the putrid smell of burnt fruit.

Among the 43 dead was Musharraf, a 30-year-old Muslim man. He was at home with his wife and children in the Bhagirathi Vihar area of Gokalpuri, north-east Delhi, when a mob of around 30 men with iron rods, knives and chains – many wearing motorcycle helmets so they could not be identified – broke down the locked door shouting jai Sri Ram.

“They cut the electricity, so it was all dark, and started smashing the house,” recounted Shakir, his brother-in-law. “His wife was calling the police but they did not come. Everyone got into the beds to hide but the men covered everything with kerosene and shouted: ‘Will you come out or do you want us to burn you alive?’.”

Shakir continued: “They smashed the bed where Musharraf was hiding underneath and he screamed, so they grabbed him and dragged him out into the street. The children ran out, too, and were screaming. His daughter, Kushi – she is just 11 – fell on the feet of those men, pleading ‘Don’t kill my father’. She tried to save him but they beat him to death in the middle of the street and threw him in the gutter.”

Like so many other Muslims in Delhi, Shakir and his family said that after the riots they could no longer stay in the city they had called home for decades and were moving back to their ancestral village. “We have never felt threatened and always lived peacefully with our Hindu brothers,” he said. “But I don’t feel safe anywhere in Delhi now.”

Violence has been a stain on India’s history since partition in 1947, when Pakistan was formed as a separate Muslim state and up to two million people died in the fighting and its aftermath. Riots have continued to erupt along religious lines in a country where around 14% of the population are Muslim, with an 80% Hindu majority. The fracturing of relations began in the 1960s and 1970s, but a flashpoint took place in 1992, when a rightwing Hindu mob of thousands, which included several members of the now ruling Hindu nationalist Bharatiya Janata party (BJP), tore down the Babri mosque in Ayodhya.

When the BJP were elected to government in 2014, led by prime minister Narendra Modi, divisions widened. The BJP is the political wing of the Rashtriya Swayamsevak Sangh (RSS), a militant Hindu nationalist paramilitary organisation that has been accused repeatedly of orchestrating attacks on Muslims. The BJP, which believes that India should be a Hindu, not a secular, nation, has fostered an environment of hate in India. Lynchings of Muslims began and Muslims have been gradually relegated to second-class citizens in their own country.

Facebook Twitter Pinterest Fellow Muslims mourn Muddasir Khan, who died in the Delhi riots. Photograph: Adnan Abidi/Reuters

Even before he became prime minister, Modi’s reputation had been tainted by hatred and violence. As chief minister of Gujarat, he had been accused of encouraging sectarian riots in 2002 that left more than 1,000 people dead, 800 of them Muslims. Modi denies the charges, which resulted in him being banned from the US. He was cleared by the Indian supreme court in 2012 but has never apologised nor expressed remorse for the killings.

His landslide re-election victory in May 2019 prompted an escalation of the Hindu nationalist agenda. But it was the passing of a citizenship amendment act (CAA) in December last year that proved the tipping point. The law, which grants citizenship for refugees of every major South Asian religion except Muslims, was widely condemned as discriminatory. Many saw it as an attempt to enshrine the Hindu nationalist agenda into law and undermine the country’s secular foundations.

The controversy has triggered India’s longest period of unrest in 40 years, with millions of people of all religions taking to the streets in protest. But the BJP response has been to ramp up their rhetoric, particularly in the recent Delhi state assembly elections. “The BJP began fermenting this crisis in Delhi weeks ago, as a way to win Hindu votes in the election,” said Ashis Nandy, a well-known political commentator.

The spark for the latest violence was provided by Kapil Mishra, a BJP leader who had just lost his seat in those elections, when he incited a Hindu mob to violently remove a group of Muslims who were blocking a road in north-east Delhi in protest against the CAA. Addressing the peaceful protest, Mishra issued an inflammatory ultimatum: “If the roads are not cleared … we will be forced to hit the streets.” Stone pelting began between Muslims and Hindus, which quickly descended into the violence that spread through the city.

But these riots were not simply neighbours turning against neighbours. Last Sunday, false rumours of a Muslim uprising spread across rightwing Hindu social media, alleging dozens of mosques in Delhi had announced over loudspeakers that they would throw all Hindus out of Delhi and that the police had arrested 32 imams. It prompted many outside Delhi to comment that they would come out to “teach our Muslim brothers a lesson”.

They kicked my stomach and my whole body. I pleaded with them not to harm my baby, but they kept kicking Muskan, 20, victim of the mob

Soon after, residents in Mustafabad, an area right on the edge of Delhi badly affected by the riots, reported seeing Hindu youths armed with machetes, metal rods and wooden sticks coming in trucks from the neighbouring states of Uttar Pradesh and Haryana. “We all saw truckloads of these mobs coming over the border from Uttar Pradesh, it was outsiders who came in and incited the violence,” said Shoaib Alam, 32. “And that then stirred up local people.”

Uttar Pradesh, whose BJP chief minister is the firebrand Hindu nationalist and openly Islamaphobic Yogi Adityanath, is a notorious hotbed of criminal activity and lawlessness. Uttar Pradesh has also been the state accused of carrying out some of the worst state-sponsored attacks, detention and torture of Muslims in a crackdown against the anti-CAA protests.

“I have not the slightest doubt that this was not a chance, spontaneous riot,” said Harsh Mander, an author and activist who is director of the Centre for Equity Studies, a Delhi research organisation. “It was certainly orchestrated and built up as part of the politics of the ruling party. I think the BJP were unnerved by the scale of the protest against the citizenship amendment law and, more specifically, that it was Hindus and Muslims coming out together in the resistance.

“It was only a matter of time before they would try and convert it into a Hindu-Muslim violent riot and encourage the most primal kind of hatred that wins them support. And after their defeat in the Delhi election, it seems this was an outlet for all the hatred they built up.”

Government spokesman Raveesh Kumar denied that the Modi government had inflamed religious tensions or had any role in the riots. “These are factually inaccurate and misleading, and appear to be aimed at politicising the issue,” he said.

In al-Hind hospital, a cramped and basic medical facility in Mustafabad which was on the frontline of the violence, Dr Meeraj Ekram looked shellshocked as he spoke of the more than 500 victims that had come through its doors since the riots began. Mainly they had gunshot wounds, but there were also stabbings, acid burns and mutilated genitalia. Police were not allowing ambulances into Mustafabad to rescue the wounded, and hundreds of patients lay on the floor.

Facebook Twitter Pinterest Burnt out shops in Delhi after the riots. Photograph: Money Sharma/AFP via Getty Images

“The injuries we were seeing were horrifying; I have never seen such terrible things in my whole life,” said Ekram. Muskan, a 20-year-old Muslim girl who was eight months pregnant, lay in a critical condition in a hospital bed after she was set upon by a Hindu mob. “They threw me to the ground, kicked my stomach and my whole body,” she whispered. “I pleaded with them not to harm my baby, I said ‘please, please’ over and over, but they kept kicking.”

Also among the patients brought into al-Hind on Tuesday night were two local imams. With a grimace, Ekram showed photos of the imam of Shiv Vihar mosque, whose face had been badly disfigured. When men had entered the mosque, the imam had attempted to run away but had been caught by the mobs, who threw a bucket of acid into his face.

Mufti Mohammad Tahir, the imam of Farooqia mosque, near Mustafabad, suffered a similar fate. He told the Observer how he had locked himself in an upper room of the mosque when the riots broke out. But police broke down the door, dragged him out and handed him to the waiting Hindu mobs, who beat him unconscious, smashing his limbs. The mosque was torched: shelves of dozens of blackened qu’rans lined one wall and a bowl containing burned fragments of Islamic religious scripture sat on a table.

Many who witnessed the riots claim that police stood by as Muslims were attacked or helped the Hindu mobs. Most of those who called the police for help did so in vain.

While the Delhi government is controlled by the progressive Aam Aadmi party (AAP), the Delhi police are under the control of the BJP minister for home affairs, Amit Shah. The police have said the focus of their investigation into the riots is on local Muslim leaders, while no BJP leaders have been charged. Delhi police were not available for comment.

Even the local politician for Mustafabad, the AAP’s Haji Yunus, described how the police ignored his requests for help. “I made several calls to the police station and they did nothing to help,” he said. “My entire government felt helpless, there was no way for us get the situation under control. There was no effort from police at all for at least two days. The police were not even allowing the ambulances through to carry out the injured people.”

Yunus said that the hatred stirred up by the BJP in the Delhi elections should be investigated. “The BJP did not think they could be defeated so badly in the election and so after they lost, they let out their frustration this way.”

Yet the prospect of holding Delhi police to account for their role in the riots through the legal system looks increasingly unlikely. Justice S Muralidhar, a judge in the Delhi high court, openly condemned the actions of the police and government last Wednesday at a hearing into the riots. But by Thursday morning, the judge was transferred to another court and the case was taken from him. The new judge gave the government four weeks to respond to the charges.

But for all the tales of discord, dozens of accounts were also given to the Observer of how Sikh and Hindu families helped save their Muslim neighbours, sheltering them in their homes as the violence broke out or helping them escape as the mobs descended.

One Hindu man, who asked to remain anonymous for fear of retaliation, spoke of how he secretly escorted seven Muslim families to safety in Shiv Vihar.

“I formed a small group involving a few other elderly Hindu neighbours and we managed to thwart the planned attacks on those Muslim households,” he said.

Meanwhile, in the Hindu-majority neighbourhood of Gokalpuri, a Sikh father, Mohinder Singh, 53, and his son Inderjit used their motorcycles to rescue around 70 Muslim men and children, the youngest just nine years old. They had been trapped in the mosque and madrasa, as a mob roamed the streets outside. Singh took the children two at a time on his bike, putting turbans on their heads as a disguise.

“I did not see if they were Muslim or Hindu, I did this for humanity,” said Mohinder. “I had to save them.”

Majinder Singh Sirsa, a Sikh leader in Delhi, said the community had opened up its gurdwaras for shelter, but had been attacked by hardline Hindu and Muslim groups for doing so. “We do feel the pain because we were also targeted 35 years ago,” he said, referring to the anti-Sikh pogroms in Delhi in 1984 where more than 3,000 Sikhs were killed. “Back then, Delhi was burning and humanity died. This week, it has happened once again.”

Shaikh Azizur Rahman contributed to this report