NEW DELHI — For decades, one of the most commonplace news items from South Asia has been the “bus plunge.”

This sort of disaster happened so frequently that foreign correspondents had to choose among bus plunges, looking for something distinctive — the passengers were pilgrims or schoolchildren; the bus fell into a ravine, or a reservoir, or the sea — to find one that was especially noteworthy, meriting coverage in the newspaper.

It is a sign of the times, in India, that we must now do the same with lynchings.

Last Friday, I found myself weighing the newsworthiness of two mob killings in different parts of the country, uncertain about which one of them we should cover. On Thursday, Junaid Khan, a 15-year-old madrasa student, was riding a crowded passenger train home from Delhi when a group of assailants, after deriding him as a “beefeater” and removing his skullcap, fatally stabbed him and threw him off the train. The same day, in Kashmir, Mohammed Ayub Pandith, a plainclothes police officer, was beaten to death outside a mosque by members of a mob who took him for an informer.

How to decide between them? I wondered.

And then I wondered, How did we get here?

It is a question others are asking, and for many liberal Indians, last weekend was when the vessel spilled over.

The hashtag #Lynchistan trended on Twitter. “May the silent be damned,” wrote the scholar Pratap Bhanu Mehta in a furious column. And Saba Dewan, a filmmaker living outside Delhi, wrote a Facebook post calling for a protest against rising violence toward Muslims and lower-caste Indians, and the idea spread with extraordinary speed, inspiring demonstrations in 11 cities. On Wednesday evening, about 2,000 people gathered at sunset in central Delhi, carrying posters with the words “Not in My Name.”

“One needs not only to protest, but to record our complete anguish,” said Amitabha Pande, a retired civil servant who voted for Narendra Modi in 2014, in the hope that as prime minister he would modernize India’s economy. He said his faith in Mr. Modi collapsed the next year, when the prime minister failed to condemn the lynching of Mohammad Ikhlaq in the village of Dadri.

“He has forgotten the fundamentals of the Constitution that he was supposed to uphold, which is the right to life,” Mr. Pande said. “The fact that he did not come out openly and condemn the Dadri murder, that is when I decided this man does not deserve to be here.”

The message seemed to have penetrated the highest levels of government, because on Thursday, in an address at the ashram where Gandhi established his nonviolence movement, Mr. Modi issued a rare condemnation of the vigilante killings. He said that cows must be protected, but within limits.

“Do we get the right to kill a human being?” he said. “Is this devotion to the cow? Is this cow protection? This cannot be the path of respected Bapuji,” he said, referring to Gandhi.

“Today, when I hear that in the name of the cow someone has been killed, I say the law should take its course; human beings have no right to take the law into their hands,” he said.

Unlike Hindu-Muslim riots, which have become less frequent in recent decades, lynchings are not counted systematically in India, nor are the death tolls dramatic enough to register to most Indians as a national crisis.

But it is clear that killings related to beef-eating or the abuse of cows, which many Hindus consider sacred, have increased in frequency since Mr. Modi was elected, according to an analysis of news coverage by IndiaSpend, a data journalism initiative. Of 63 attacks recorded since 2010, 61 took place under Mr. Modi’s government. Twenty-four out of the 28 people killed in the attacks were Muslim. During the first six months of 2017, there were 20 cow- or beef-related attacks, a jump from the same period in 2016.

There is no evidence that the violence has politically damaged Mr. Modi, who remains extremely popular across a variety of demographic groups. Indeed, many Hindus who came out to protest said they had friends and family who shrugged off the killings as justified by India’s history of invasion by Muslims.

“They are pretty indifferent,” said Shivani Kasumra, 20, a university student, of her own middle-class relatives. “They say this is retribution, that they are terrorists, and that they will convert Hindus to Islam. This is a common Hindu sentiment. Somehow they feel wronged.”

In Delhi, the activists gathered on a street set aside for public protest, and they listened as Mohammad Asaruddin, a relative of the 15-year-old killed last week, read a letter in Hindi, which he said contained a last message to the victim’s mother.

“Dear Ma, I am home,” it said. “You wanted me to buy new clothes from Delhi, but fate has landed me in heaven, where you don’t have marauding mobs. I am home. Yours, Junaid.”

Many reporters had not visited the street for several years, since the vast anticorruption movement that helped sweep the Indian National Congress party out of power. Among the protesters were a number of figures shut out from the new right-wing order, including Swami Agnivesh, a Hindu holy man staunchly associated with Congress party causes; a transgender woman who introduced herself as Vqueeram; and Tehseen Poonawalla, a political trend-watcher and the debonair son of an industrialist. Two hours later, they filed out into the humid darkness, murmuring hopefully to one another about the movement they hoped would grow out of the event.

But the more realistic among them acknowledged that Mr. Modi faces no formidable political opposition and is likely to win a second five-year term in 2019. Shivam Vij, the deputy editor of HuffPost India, said in advance that protesting the killings was a futile exercise and that he would not pretend otherwise.

“It does no damage whatsoever to Modi and his party, because what this protest says is, ‘Muslims are getting lynched,’ and a lot of Hindutvas out there will say, ‘That’s the point,’ ” Mr. Vij said, referring to far-right Hindus. “Society at large is turning right-wing. How long that crest is going to be is the most interesting question, and the fact is nobody knows. Not anytime soon.”