New Delhi (CNN) Deadly protests erupted across India Sunday over a controversial citizenship bill that critics fear could further marginalize the country's minority Muslim community.

Protests broke out across nine states, including in major cities such as Kolkata, Mumbai, Chennai, Hyderabad and the capital New Delhi, mostly around university campuses. Meanwhile, ongoing protests in Assam, in India's northeast, turned violent, with at least five people killed, police said.

In Delhi, students began demonstrating at the prestigious Jamia Milia Islamia university early Sunday, with around 2,000 people taking part at the protest's peak. Hundreds of people were injured in the protests, and dozens arrested, as well as significant damage to the campus, said Najma Akhtar, the university's vice chancellor.

Protesting students from the university told CNN they were beaten with batons and sticks, leaving 200 injured according to the university administration.

But this contradicts the Delhi Police's version, who say they were unarmed and used minimum force to bring the crowds under control.

Demonstrators shout slogans during a shutdown called by the North East Students' Organization in Agartala, India, on December 10. It was hours after lawmakers approved the government's new citizenship bill.

Demonstrators shout slogans during a shutdown called by the North East Students' Organization in Agartala, India, on December 10. It was hours after lawmakers approved the government's new citizenship bill.

Protesters on motorbikes hold placards during a protest against the bill in Guwahati on Tuesday, December 10.

Protesters on motorbikes hold placards during a protest against the bill in Guwahati on Tuesday, December 10.

Security personnel use batons to disperse students protesting against CAB in Guwahati on December 11.

Security personnel use batons to disperse students protesting against CAB in Guwahati on December 11.

Indian youth congress members hold torches as they demonstrate in New Delhi on Wednesday, December 11.

Indian youth congress members hold torches as they demonstrate in New Delhi on Wednesday, December 11.

An Indian police officer aims his gun before firing toward protesters who threw stones in Guwahati on December 12.

An Indian police officer aims his gun before firing toward protesters who threw stones in Guwahati on December 12.

Indian Muslims demonstrate against the bill in New Delhi on December 13.

Indian Muslims demonstrate against the bill in New Delhi on December 13.

Relatives of Sam Stafford, 18, who was killed during clashes with police the previous day, react in Guwahati on December 13.

Relatives of Sam Stafford, 18, who was killed during clashes with police the previous day, react in Guwahati on December 13.

A bus is seen on fire following a demonstration in New Delhi on Sunday, December 15.

A bus is seen on fire following a demonstration in New Delhi on Sunday, December 15.

Students and activists protest outside the Allahabad University campus in Allahabad, India, on Monday, December 16.

Students and activists protest outside the Allahabad University campus in Allahabad, India, on Monday, December 16.

People standing on roofs in New Delhi watch police gathered next to a demonstration on December 17.

People standing on roofs in New Delhi watch police gathered next to a demonstration on December 17.

Students from Jamia Millia Islamia, a university in New Delhi, shout slogans during a protest on Tuesday, December 17.

Students from Jamia Millia Islamia, a university in New Delhi, shout slogans during a protest on Tuesday, December 17.

Chief minister of West Bengal state and leader of the Trinamool Congress Mamata Banerjee, along with party supporters, walks in a mass rally across Howrah bridge in Kolkata on December 18.

Chief minister of West Bengal state and leader of the Trinamool Congress Mamata Banerjee, along with party supporters, walks in a mass rally across Howrah bridge in Kolkata on December 18.

An officer flees a police station damaged by protesters during a demonstration in Lucknow on December 19.

An officer flees a police station damaged by protesters during a demonstration in Lucknow on December 19.

Protesters gather by the Jama Masjid mosque in New Delhi to demonstrate against India's new citizenship law on Friday, December 20.

Protesters gather by the Jama Masjid mosque in New Delhi to demonstrate against India's new citizenship law on Friday, December 20.

Demonstrators sit next to bonfires during dusk as they block a road during a protest in New Delhi on Sunday, December 22.

Demonstrators sit next to bonfires during dusk as they block a road during a protest in New Delhi on Sunday, December 22.

Demonstrators gather at the Quddus Saheb Eidgah grounds to take part in a rally against India's new citizenship law in Bangalore on Monday, December 23.

Demonstrators gather at the Quddus Saheb Eidgah grounds to take part in a rally against India's new citizenship law in Bangalore on Monday, December 23.

Protestors shout slogans outside the Delhi Police Headquarters following clashes between student groups at Jawaharlal Nehru University in New Delhi on Sunday, January 5. The violence injured around 34 people, according to police.

Activists of All Assam Students' Union and other indigenous organizations participate in a torch procession against the Citizenship Amendment Act in Guwahati, India, on Saturday, January 11.

Activists of All Assam Students' Union and other indigenous organizations participate in a torch procession against the Citizenship Amendment Act in Guwahati, India, on Saturday, January 11.

Police personnel try to protect a man attending a protest against graffiti on the shutters and walls of Church Street condemning Indian Prime Minister Narendra Modi and India's new citizenship law in Bangalore on Tuesday, January 14.

Police personnel try to protect a man attending a protest against graffiti on the shutters and walls of Church Street condemning Indian Prime Minister Narendra Modi and India's new citizenship law in Bangalore on Tuesday, January 14.

Protesters light candles near posters of Mahatma Gandhi and politician and social reformer Bhimrao Ramji Ambedkar during a demonstration against India's new citizenship law at Mansoor Ali Park in Allahabad on Tuesday, January 14.

Protesters light candles near posters of Mahatma Gandhi and politician and social reformer Bhimrao Ramji Ambedkar during a demonstration against India's new citizenship law at Mansoor Ali Park in Allahabad on Tuesday, January 14.

A heart made of paper boats with slogans on them rests near a protest in the Shaheen Bagh neighborhood in New Delhi on Wednesday, January 16.

A heart made of paper boats with slogans on them rests near a protest in the Shaheen Bagh neighborhood in New Delhi on Wednesday, January 16.

A Muslim youth waves the Indian flag during a protest held by the Muslim community in Bangalore on January 24.

A Muslim youth waves the Indian flag during a protest held by the Muslim community in Bangalore on January 24.

An Indian Muslim participates in a protest against a new citizenship law that opponents say threatens India's secular identity, in Mumbai, India, on Friday, January 24.

An Indian Muslim participates in a protest against a new citizenship law that opponents say threatens India's secular identity, in Mumbai, India, on Friday, January 24.

What is the Citizenship Amendment Bill?

Anger has been growing nationally over the Citizenship Amendment Bill (CAB), which was signed into law last week. The bill promises to fast-track citizenship for religious minorities, including Hindus, Sikhs, Buddhists, Jains, Parsis and Christians, from Afghanistan, Bangladesh and Pakistan who arrived before 2015.

But the exclusion of Muslims -- which Indian Prime Minister Narendra Modi says is because they are not minorities in India's neighboring countries -- has raised concerns about the bill's constitutionality and the growing anti-Muslim rhetoric in India.

Many in Assam and Tripura, states in India's northeast, also fear that it could see large numbers of Hindus migrating to the region, outnumbering the region's 200 distinct indigenous groups and changing its religious and ethnic makeup.

There are around 16 million Hindus in Bangladesh alone, and naturalizing large numbers of immigrants could also greatly impact employment, government subsidies and education.

Violent protests on the Citizenship Amendment Act are unfortunate and deeply distressing.



Debate, discussion and dissent are essential parts of democracy but, never has damage to public property and disturbance of normal life been a part of our ethos. — Narendra Modi (@narendramodi) December 16, 2019

Students recall police brutality

The protest at Jamia Milia Islamia was not organized by the university or its students, according to its vice chancellor Najma Akhtar. "From the areas around the university, a call had gone out for an organized protest," she said.

Akhtar said protesters broke through a gate at the university, pushing guards aside, then hid in a college library. She said some students were beaten by police officers in the library and were being treated for their injuries.

Akhtar said police did not have permission to come on campus. Some students told Indian media that officers forced their way into student accommodation and the library and dragged students out.

Right Now outside @DelhiPolice HQ at ITO



Protests against the violence at #JamiaProtest



Video Crtsy : @suhasmunshi pic.twitter.com/GEZH3N4axf — Shreya Dhoundial (@shreyadhoundial) December 15, 2019

One student protester, 21-year-old Hanzala Mojibi, said he was among the group who ran from the police advance into the library.

"We were about 200-300 people who were trapped inside," he told CNN. "We tried to negotiate with the police to not use violence. But they surrounded us and took our phones and broke them. They broke the CCTV cameras installed there."

Mojibi said police "abused and humiliated us."

"We were made to kneel on the ground for 30 minutes and at any time they heard any students resisting, they would beat us in retaliation," he added. "Afterward they told us to leave the college."

Meanwhile Delhi Police spokesperson, MS Randhawa, told reporters Monday that the police used "maximum restraint" and "minimum force" throughout the weekend's protests.

He added that protesters threw "bulbs" and "bottles" at police, set buses on fire, and damaged around 100 vehicles. Dozens of officers were injured in the incident, said Randhawa.

Protesters gather outside Jamia Milia Islamia University in India on Monday, covering their mouths to signify the loss of free speech in the country.

On Monday, the university library where the students had taken refuge was a scene of devastation. CNN reporters found doors and windows smashed, glass littering the floor, abandoned shoes, and overturned tables and chairs.

Security cameras were also broken -- which students said police had done.

A few hundred students still gathered outside the university gates, holding placards calling for justice and secularism. Most were men, with many female students having left in fear following Sunday's violence, those still remaining told CNN.

'A dark day'

Prime Minister Modi and his Bharatiya Janata Party (BJP) have described the citizenship bill as a means of protecting vulnerable groups from persecution. Modi sought to reassure citizens Monday, saying in a statement that the new citizenship bill will "not affect any citizen of India of any religion."

He added that the bill "is only for those who have faced years of persecution outside and have no other place to go, except India."

Critics, meanwhile, say the true target is India's minority Muslim population and that it risks undermining the country's secular constitution.

"Today marks a dark day in the constitutional history of India," Sonia Gandhi, president of the opposition Congress Party, said in a statement Sunday. "The passage of the citizenship amendment bill marks the victory of narrow-minded and bigoted forces over India's pluralism."

At least five people died in the protests in the region Sunday, with more than a hundred people injured, including police officers, said police official G. P. Singh. He added the government was reviewing whether to restore internet access.