Three dead in widespread protests across India despite bans on public gatherings

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

Several metro stations were closed, with Delhi Metro Rail Corporation citing "sudden safety and security reasons." Heavy traffic also prompted airlines Air India and Indigo to offer a full refund for all outbound domestic and international flights from the capital.

Large crowds also gathered in major cities including Mumbai, Kolkata, Hyderabad 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.