BEIJING — Beijing’s Tiananmen Square had checkpoints and police vehicles on Tuesday as Communist China tried to silence the 35th anniversary of a bloody crackdown on pro-democracy protests.

Hong Kong police arrested four people and swarmed a handful of others who tried to protest or commemorate as the effort extended beyond the mainland.

China has long quashed any public memory of the military crackdown on months-long protests at the heart of its capital. An estimated 180,000 troops and police rolled in with tanks and armored vehicles and fired into crowds trying to block them from advancing on the student-led demonstration in the square

Hundreds, if not thousands, are believed to have been killed in an overnight operation that ended on the morning of June 4, 1989.

It was a turning point in modern Chinese history as Communist Party hardliners embraced control instead of political reforms.

The economy boomed in the ensuing decades, turning a once impoverished country into the world’s second largest economy, but societal controls have been tightened since President Xi came to power in 2012.

Across China, the anniversary remains a taboo subject that is heavily censored. Any mention on social media is quickly erased.

Life appeared as normal at Beijing on Tuesday, with tourists lining the streets leading to gates to Tiananmen Square and the Forbidden City, the former imperial palace across from it. The closest subway exit was closed, as was a viewing point atop Tiananmen Gate, according to a visitor registration website.

“As to the political disturbance that occurred in the late 1980s, the Chinese government has long had a clear conclusion,” a Foreign Ministry spokeswoman, Mao Ning, said without elaborating.

Asked about Western government statements on the anniversary, she added, “We are firmly opposed to anyone using this as a pretext to attack and smear China and interfere in China’s internal affairs.”

Tiananmen Mothers, a group formed by families of the victims, made an online appeal to the Chinese government to publish the names and total number of those who died, grant compensation to the victims and their relatives, and pursue legal accountability for those responsible.

“The June 4 tragedy is a historical tragedy that the Chinese government must face and explain to its people, and some people in the government at that time should be held legally responsible for the indiscriminate killing of innocents,” the group said in a letter signed by 114 family members and published on its website, which is blocked in China.

Tiananmen memorials were also scrubbed out at Hong Kong — for years the only place in China where they could take place. A carnival organized by pro-Beijing groups was held Tuesday in a park that for decades was the site of a huge candlelight vigil marking the anniversary.

Police officers were out in force.

An elderly man was seen being taken away after holding up two handwritten posters. One read: “Remember 89! Mourn 64!” Hong Kong press said that activist Alexandra Wong, popularly known as “Grandma Wong,” was also removed after she chanted slogans.

An AP journalist saw another woman taken away after being searched, and an online Hong Kong press outlet reported a fourth person taken in a police vehicle. In both cases it was unclear why.

“It’s different from the past,” one Hong Kong resident, Keith Law, said. “Many people seem to act as if there’s nothing happening, including myself.”

After darkness fell, one person who lit a candle and two others who turned on their smartphone lights were quickly cordoned off by police and questioned in three separate incidents outside the park. They were eventually released.

“My heart hasn’t died yet,” one former vigil-goer, Edward Yeung, said.

A woman who wore a T-shirt with the numbers 8964 in Roman numerals was taken away by police, however.

Rows of electronic candles lit up the dozens of windows of the American consulate at night, and the British consulate posted an image on the social media platform X of a hand holding up a smartphone with its light on and the Roman numerals “VIIV,” a reference to June 4. Hong Kong is a former British colony.

Some Hong Kong residents remembered the event privately, running 4 miles on Monday or sharing Tiananmen-related content on social media.

Late Tuesday, police said they arrested four people aged between 23 and 69. Among them was a 68-year-old woman detained on suspicion of sedition under the city’s new national security law. Police said she had chanted slogans in public.

Two others were accused of assaulting police officers and disorderly conduct in a public place. The remaining suspect was arrested for alleged common assault. Police didn’t identify them.

Authorities also said five other people suspected of “breaching public peace” were taken for further investigation, but all were later released.

Hong Kong leader John Lee did not answer directly when asked Tuesday whether residents could still publicly mourn the crackdown. He urged residents not to let down their guard against any attempts to cause trouble.

“The threat to national security is real,” Mr. Lee said at a weekly briefing. “Such activities can happen all of a sudden, and different people may use different excuses to hide their intention.”

Commemorative events have grown overseas in response to the silencing of voices at Hong Kong. More than 100 people gathered at Washington, D.C., to light candles on Monday at the foot of a replica of a statue erected on the square during the 1989 protest — a woman holding a torch and known as the Goddess of Democracy.

“Chinese people cannot speak for themselves, so we must speak for them,” said political commentator Gordon Chang.

That sentiment was echoed in Free China, where people laid flowers and put electronic candles on the numbers 8964 — representing June 4, 1989 — on a banner spread on the ground at Taipei, the capital. Taiwan is a self-governing democratic island that China claims as its territory.

“As long as other places can still protest, we must continue to protest,” resident Leo Chiang said.