Critics accuse Hindu nationalists of wanting to discriminate against Muslims and that the law is jeopardizing India as a secular state.

The clashes in Delhi have mainly taken place in the Muslim suburbs of the city, but among the roughly 20 death victims, and so far more than 200 hospitalized, there are both Muslims and Hindus.

Eyewitnesses speak of crowds wandering around with stones and stones, and burnt down Muslim shops, residential buildings and unholy mosques. Muslims flee their homes following the wave of violence that many believe may continue.

Some Hindu nationalists did not want to embarrass Prime Minister Modi during the prestigious visit of President Trump. Now that the visit is over, the same group may feel more free to resort to violence and the situation worsens.

Want to call in the army

Delhi Chief Minister Arvind Kejriwal in a tweet called the situation alarming:

"Despite the efforts of the police, it was not possible to control the situation and in order to instill confidence, the army should be called in and curfew imposed in the affected areas immediately."

However, the police representatives say they have sufficient numbers of police officers evacuated and that the population must trust the police and that there is no reason to be afraid.

The law applies to all except Muslims

But the protests have been going on for months in India, both before and after the Citizenship Act was introduced. The law makes it easier for non-Muslim refugees from neighboring Bangladesh, Pakistan and Afghanistan to gain Indian citizenship - thus the law applies to all South Asia's major faiths except Muslims.

The fear among critics is that religious affiliation becomes an important element in the right to citizenship. India's Prime Minister Narendra Modi and his government deny this, saying that they are only giving citizenship to persecuted minorities.