For 30 years, China’s Communist Party has worked hard to erase the memory of the massacre on June 4, 1989.

Much of the world is aware that hundreds, perhaps thousands, of people died as tanks and troops rolled through Tiananmen Square in the heart of the capital Beijing, ending the student-led struggle for a more open society. But a news blackout at the time meant that many Chinese were unaware the killings took place until well after the fact.

The censorship continues to this day. References to Tiananmen—even simple images of candles, or playing cards showing the numbers 6 (for June) and 4—are kept off the heavily redacted Chinese internet. Parents who lost children are prevented from paying tribute to their deceased sons and daughters. Activists and outspoken dissidents are detained as the anniversary approaches. And many young Chinese grow up unaware of what happened that humid night 30 years ago.

On the rare occasions when party officials mention June 4, 1989—as defense minister Wei Fenghe did last Sunday—it mostly sticks to a script: the military crackdown was the “correct” decision, as it ensured the nation’s stability and future economic development. The army officers who dare to voice dissenting opinions do so anonymously—such as the two veterans who told Hong Kong’s South China Morning Post that many in the army felt “guilt and shame” over the killings.

On the 30th anniversary of a massacre China would like to blot out from its citizens’ collective memory, TIME spoke to young Chinese about what it’s like to stumble across a history they were not supposed to discover.

Some names have been changed to protect the identities of those interviewed.

Crystal Xu, 22, a journalism student in Hong Kong

For Crystal Xu, Hong Kong’s pro-democracy movement served as a gateway into learning about the June 4 massacre. She came to Hong Kong in 2014, to study journalism in the wake of 79-day protest that galvanized the city, and wanted to know more about social movements in China. Her reading led her to Tiananmen.

“I don’t know if my friends know about this. Nobody [on the] mainland would talk about June 4th and nobody told me about June 4th before,” the 22-year-old student says.

Xu adds that she is aware of arguments that the students weren’t “100 percent correct,” but wishes the issue could be debated back home. “I believe the matter should be discussed publicly and we should rethink it,” she says. On the 30th anniversary, she is braving the censors to help educate her friends, and has posted a collection of links to articles and interviews about Tiananmen on WeChat, China’s biggest social messaging platform. The post has yet to be removed, but another of her social media accounts has been taken offline. “I told my friends not to report me,” she says.

Bob Zhang, 29, a research assistant in Hong Kong

Bob Zhang says he first heard about the Tiananmen massacre as a child, listening to outspoken relatives debating politics. It was mentioned again on broadcasts aired by U.S.-run Voice of America when he was a high school student in Shanghai. But it wasn’t until 2005, while studying at Peking University, that he happened across a documentary, simply called Tiananmen, that was shared on a university intranet set up to share banned information. For the first time, he saw the iconic images that had shocked the world: students rallying in the square, soldiers leaping over barricades and a lone man defying a column of tanks. “It was a transgression watching something like this. I was pretty shocked,” he says.

Zhang says he doesn’t think remembering Tiananmen necessarily means assuming a political stance. “It’s more about preventing it from being forgotten. When history has been deliberately erased, there is a price to be paid: we haven’t learned the lessons.”

Yaqiu Wang, 31, China researcher for Human Rights Watch in New York City

“It was really disorienting,” Yaqiu Wang says of the moment she stumbled across a mention of the Tiananmen Square massacre while surfing the web in an internet café in her hometown in southern Zhejiang Province. “The blood was gory, shocking and confusing.”

Wang was just one-year-old in 1989 and heard nothing of the massacre during her childhood. After graduating high school in 2005, she often engaged in political discussions online. That’s when she first saw photos of the brutal military crackdown. She says that censorship was not as strict back then and people were hopeful that the internet might bring more openness to China. Learning about June 4 completely changed her perspective, she says.

“It made me realize the extent the Chinese government is willing to go to suppress dissent, even completely peaceful dissent,” she says. “Who can really say they won’t do it again?”

R. Sun, 29, a student in Shanghai

Before coming to Hong Kong, R. Sun says the only time he heard the mysterious term “June 4th” was during a high school history class. The teacher briefly mentioned the date, explaining that this part of history was not in the textbook because it was deliberately erased. Then in 2009, the Nanjing native moved to Hong Kong, and noticed posters around his university campus announcing memorials for the 20th anniversary of the Tiananmen massacre. The posters’ reference to June 4, 1989 reminded him of a date he had almost forgotten.

“I’ve been told lies,” he says of realizing that he had been fed propaganda.

Every year, he now commemorates June 4 in some way, fasting, taking part in vigils, or creatively using the numbers 8, 9, 6 and 4. He says he is flying from Shanghai to Hong Kong to take part in the 30th anniversary vigil in Hong Kong. “June 4th has shaped [me] and is a part of who I am today,” he says.

—With reporting by Amy Gunia, Hillary Leung, Emily Peng and Lily Lin / Hong Kong

Contact us at letters@time.com.