A suspected Hindu nationalist opened fire at student protesters outside New Delhi's Jamia Millia Islamia University on Thursday. The protesters were holding a rally against a citizenship law they say discriminates against Muslims.

A video shows the young man brandishing a handgun on the street, where more than 1,000 protesters had gathered for a march. And meters away dozens of police officers looked on outside the university.

"He was in front of all the people – protesters and policemen who were standing nearby, but he jumped in from this side, brandished the gun and said, 'Come, I will give you freedom,'" one witness told Reuters.

Pointing the gun towards protesters, he taunted the demonstrators, and as both protesters and police converged towards him to try and calm down the situation, he fired a single shot at a man later identified as Shadab Farooq, who was shot in the hand and now is receiving treatment in a hospital

Minutes before firing, the gunman went live on Facebook saying this will be his "final journey" and urging readers to "remember his family". He had also posted photos of himself posing with a gun, where he is seen wearing a saffron T-shirt, the color of Hindu nationalists.

Facebook later said it had taken down the gunman's account. "There is no place on Facebook for those who commit this kind of violence," the platform said in a statement.

"We have removed the gunman's Facebook account and are removing any content that praises, supports or represents the gunman or the shooting as soon as we identify it."

Police said they had detained the suspect but gave no further details.

Following the shooting, the number of protesters swelled to several thousand, and scuffles between them and several hundred police officers broke out.

The incident is the first known case where a civilian has shot at protesters in the Indian capital following the months-long protests against the controversial Citizenship Amendment Bill (CAB) which fast-tracks citizenship for religious minorities, including Hindus, Sikhs, Buddhists, Jains, Parsis and Christians, from Afghanistan, Bangladesh and Pakistan, but excluding Muslims.

The bill was passed by India's parliament last December. The government, ruled by the Hindu nationalist Bharatiya Janata Party (BJP), said the bill seeks to protect religious minorities who fled persecution in their home countries.

However, opposition parties say the bill discriminates against Muslims and is unconstitutional as it bases citizenship on a person's religion and would further marginalize India's Muslim minority of about 200 million people.