(CNN) Deadly protests erupted in at least 15 cities in India Thursday, despite strict bans on public gatherings in several areas, as public anger over a controversial new citizenship law considered by many to be discriminatory against Muslims continues to build.

At least three people died in the violence, as thousands took to streets across the country. Two people died from injuries sustained during a protest in the city of Mangalore, in the southern state of Karnataka, a senior doctor at the Highland Hospital told CNN. One more person died from firearm injuries during a protest in Lucknow, the capital of northern Uttar Pradesh state, according to a senior doctor at the King George Medical University in the city.

In Uttar Pradesh, protesters and police violently clashed in Lucknow, with buildings and vehicles set alight. And in Sambhal city buses were torched by protesters.

In the capital New Delhi attempts by authorities to prevent demonstrations proved ineffective, as large crowds brought parts of the downtown area to a standstill.

Large crowds also gathered in major cities including Mumbai, Kolkata, Hyderabad, Malegaon , and Chennai. By midday, police had detained 70 people in the southern city of Bengaluru after protesters refused to disperse from two locations.

Fueling the protests is nation-wide anger over the Citizenship Amendment Act (CAA), which was signed into law last week. The law promises to fast-track Indian citizenship for religious minorities from three neighboring countries who arrived before 2015 -- but not if they are Muslim.

Critics say the law is unconstitutional as it bases citizenship on a person's religion and would further marginalize India's 200-million strong Muslim community.

Photos: Protesters rally against India's citizenship bill 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. Hide Caption 1 of 33 Photos: Protesters rally against India's citizenship bill A Muslim youth waves the Indian flag during a protest held by the Muslim community in Bangalore on January 24. Hide Caption 2 of 33 Photos: Protesters rally against India's citizenship bill 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. Hide Caption 3 of 33 Photos: Protesters rally against India's citizenship bill 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. Hide Caption 4 of 33 Photos: Protesters rally against India's citizenship bill 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. Hide Caption 5 of 33 Photos: Protesters rally against India's citizenship bill 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. Hide Caption 6 of 33 Photos: Protesters rally against India's citizenship bill 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. Hide Caption 7 of 33 Photos: Protesters rally against India's citizenship bill Placards lie next to Indian Muslims offering prayers during a protest on Saturday, January 4. Hide Caption 8 of 33 Photos: Protesters rally against India's citizenship bill Policewomen detain a student protesting outside Uttar Pradesh Bhawan in New Delhi on Friday, December 27. Hide Caption 9 of 33 Photos: Protesters rally against India's citizenship bill 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. Hide Caption 10 of 33 Photos: Protesters rally against India's citizenship bill Demonstrators sit next to bonfires during dusk as they block a road during a protest in New Delhi on Sunday, December 22. Hide Caption 11 of 33 Photos: Protesters rally against India's citizenship bill Protesters gather by the Jama Masjid mosque in New Delhi to demonstrate against India's new citizenship law on Friday, December 20. Hide Caption 12 of 33 Photos: Protesters rally against India's citizenship bill Policemen with batons charge a protester in Ahmedabad on Thursday, December 19. Hide Caption 13 of 33 Photos: Protesters rally against India's citizenship bill Indians gather during a protest rally in Mumbai on December 19. Hide Caption 14 of 33 Photos: Protesters rally against India's citizenship bill An officer flees a police station damaged by protesters during a demonstration in Lucknow on December 19. Hide Caption 15 of 33 Photos: Protesters rally against India's citizenship bill 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. Hide Caption 16 of 33 Photos: Protesters rally against India's citizenship bill Students from Jamia Millia Islamia, a university in New Delhi, shout slogans during a protest on Tuesday, December 17. Hide Caption 17 of 33 Photos: Protesters rally against India's citizenship bill People standing on roofs in New Delhi watch police gathered next to a demonstration on December 17. Hide Caption 18 of 33 Photos: Protesters rally against India's citizenship bill Students and activists protest outside the Allahabad University campus in Allahabad, India, on Monday, December 16. Hide Caption 19 of 33 Photos: Protesters rally against India's citizenship bill People participate in a mass rally in Kolkata, India, on December 16. Hide Caption 20 of 33 Photos: Protesters rally against India's citizenship bill Demonstrators hold signs at the University of Mumbai. Hide Caption 21 of 33 Photos: Protesters rally against India's citizenship bill A bus is seen on fire following a demonstration in New Delhi on Sunday, December 15. Hide Caption 22 of 33 Photos: Protesters rally against India's citizenship bill A child prays during a condolence event in Guwahati, India, for demonstrators killed in anti-CAB protests. Hide Caption 23 of 33 Photos: Protesters rally against India's citizenship bill Demonstrators shout slogans during a protest in Guwahati on Friday, December 13. Hide Caption 24 of 33 Photos: Protesters rally against India's citizenship bill Relatives of Sam Stafford, 18, who was killed during clashes with police the previous day, react in Guwahati on December 13. Hide Caption 25 of 33 Photos: Protesters rally against India's citizenship bill Indian Muslims demonstrate against the bill in New Delhi on December 13. Hide Caption 26 of 33 Photos: Protesters rally against India's citizenship bill Police fire tear gas during a protest in Guwahati on Thursday, December 12. Hide Caption 27 of 33 Photos: Protesters rally against India's citizenship bill Indian soldiers patrol near a burnt vehicle during a curfew in Guwahati on December 12. Hide Caption 28 of 33 Photos: Protesters rally against India's citizenship bill An Indian police officer aims his gun before firing toward protesters who threw stones in Guwahati on December 12. Hide Caption 29 of 33 Photos: Protesters rally against India's citizenship bill Indian youth congress members hold torches as they demonstrate in New Delhi on Wednesday, December 11. Hide Caption 30 of 33 Photos: Protesters rally against India's citizenship bill Security personnel use batons to disperse students protesting against CAB in Guwahati on December 11. Hide Caption 31 of 33 Photos: Protesters rally against India's citizenship bill Protesters on motorbikes hold placards during a protest against the bill in Guwahati on Tuesday, December 10. Hide Caption 32 of 33 Photos: Protesters rally against India's 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. Hide Caption 33 of 33

Colonial-era law

The Indian government had sought to quell any unrest over the law's passing. Last week, authorities shut down the internet in four northeastern states after violent protests broke out. And on Thursday, a colonial-era law that prevents gatherings of four or more people -- known as Section 144 -- was imposed in three areas.

New Delhi police imposed Section 144 around the Red Fort ahead of Thursday's protest, after police denied permission for the march. The law was also imposed in Bengaluru, and across the entire state of Uttar Pradesh -- India's largest and most populous.

Organizers of nationwide action called for people to gather regardless of the prohibitory restrictions. "Section 144 being imposed by the police is an attempt to thwart our march. This will not deter us. We will gather there for our march," Yogendra Yadav, founder of Swaraj Abhiyaan, a group that organized the march told CNN ahead of Thursday's march in Delhi.

Many of who marched said the government is using bans on public gatherings to muzzle the voices of Indian people.

"This was to be a peaceful protest by citizens who wish to uphold the values of our Constitution. You have used a colonial-era law to suppress us and our voices," India historian Ramachandra Guha wrote on his official Twitter account on Thursday.

In New Delhi, telecoms company Vodafone India tweeted that its services had been suspended in several parts of the city, "as per the directive received from the government." It comes amid reports in multiple local media outlets that the government ordered the suspension of mobile and data services in parts of the capital as protests got underway.

Vodafone tweeted in a reply to a customer that services were stopped in six locations across the city. CNN has reached out to local authorities for confirmation.

Outside of Delhi's Red Fort, demonstrators said it was their right to protest.

"What they're doing is wrong. We oppose the CAA. We oppose not being allowed to protest. We are Indian and Muslim. We can be both. All religions can live in India," said local resident Rubina Zafar.

Protests escalate

The restrictions come after ongoing protests against the citizenship law have turned violent in recent days, with police and protesters involved in street clashes.

Hundreds of people were injured and dozens arrested on Sunday after police stormed a university campus in New Delhi, firing tear gas. And on Tuesday further violent clashes between protesters and police broke out in the district of North East Delhi.

In the northeastern state of Assam ongoing protests have turned deadly, with at least five people killed, police said.

Protests in the northeast are different, however. Many indigenous groups there fear that giving citizenship to large numbers of immigrants would change the unique ethnic make-up of the region and their way of life, regardless of religion.

The widespread civil action comes a day after India's Supreme Court refused to halt implementation of the citizenship law, though it will hear a raft of petitions that question the law's constitutionality.

"It hurts the spirit of India. We are going to fight this till the end," said Abhishek Manu Sanghvi, a senior leader from India's main opposition Congress Party on Wednesday.