The 17-year-old boy left his home in a small north Indian town on Thursday morning after telling his grandfather he was going to school. Instead, he turned up 80 km away in New Delhi, where he pulled out a gun and shot an anti-government protester.

The incident, captured in dramatic pictures on Thursday, was the first time a civilian had opened fire on protesters in the capital, raising fears that more Indians would take the law into their own hands as sometimes deadly protests rock the country.

A new law brought in by the Hindu-nationalist government that fast-tracks Indian citizenship for non-Muslim minorities from three neighbouring countries has divided opinion, as critics say it discriminates against Muslims.

Family members, neighbours, and a school official in Jewar described the boy — who cannot be named under Indian law because he is under 18 — as quiet and ordinary. His act of violence took them by surprise.

In social media posts and conversations with some classmates, he spoke of restoring Hindu pride and expressed admiration for a right-wing activist whom police have accused of fomenting violence.

"He wanted to do things for Hindus, he had that in his heart," classmate Shivam told Reuters, giving only his first name. "For years, he had said he was going to do something big."

Reuters has not been able to establish how the boy planned the attack outside Delhi's Jamia Millia Islamia university or how he acquired the rudimentary gun. He fired a single shot, wounding a protester in the hand.

WhatsApp messages with another classmate, seen by Reuters, show that he asked for several thousand rupees three days before the shooting incident, without revealing why.

Upheaval and division

Since December, when the citizenship law was passed, hundreds of thousands of people have taken to the streets, saying the legislation is anti-Muslim and against the spirit of India's secular constitution. At least 25 people have been killed in clashes with police.

Prime Minister Narendra Modi's government says the law is designed to help persecuted minorities from Afghanistan, Bangladesh and Pakistan.

In recent days, some leaders from the ruling party have called for action against protesters opposed to the law, whom they accuse of being unpatriotic.

Junior finance minister Anurag Thakur this week encouraged supporters at a state election rally in New Delhi to chant slogans calling for traitors to be shot. He was reprimanded by Indian's election commission.

Hours after the shooting, small groups of people walked past the boy's house in Jewar, shouting Hindu slogans in support of his actions.

"What he did was unconstitutional, but we are with him," a neighbour said, declining to be named.

Hindus, Muslims and members of smaller religious minorities live cheek-by-jowl in Jewar, typical for towns and cities in Uttar Pradesh, Indian's most populous state.

Disbelief and some admiration

Family members said the boy usually split his time between school and home, which adjoins his father's small sweet shop, and mostly kept to himself. In recent days, he had become even more withdrawn, spending a lot of time on his phone.

"We tried talking to him but we couldn't get him to open up," said his father.

"I'm still not able to understand what happened," added the boy's grandfather, wrapped under a blanket in their family home in a crowded lane dotted with shops and Hindu temples.

On his two known Facebook accounts, which have been taken down by the company, he posted calls for Hindus to unite. Some posts featured him posing with weapons, according to a Reuters review of his profiles before they were removed.

Police, who are holding the boy in custody, could not be reached for comment on their investigation.

In March 2018, the boy asked friends via Facebook to join a meeting of the Bajrang Dal, a hardline Hindu group tied to the ruling Bharatiya Janata Party. Days later, he shared photos of himself at the meeting.

Praveen Bhati, a local leader from the Bajrang Dal, denied the boy was a member of the group.

Some classmates said they were aware of his support for Hindu nationalism for at least three years, partly from his social media posts.

The classmates said he idolised right-wing activist Deepak Sharma, whom police accused of instigating violence against students from Afghanistan at a north Indian university in 2018.

At least two social media profiles of the boy — on Facebook, and WhatsApp — had Sharma in the main display picture.

Sharma said he remembered meeting the boy and recognised a photograph with him.

"I am not in touch with him," Sharma told Reuters, adding that he had quit activism.