Tiananmen: "We still don't know what happened"

China hides history in attempt to conceal Tia... 03:54

BEIJING -- Even 25 years later, the violent crackdown at Tiananmen Square in Beijing is a story the Chinese government does not want told.

CBS News correspondent Seth Doane and his team had trouble finding people who would even speak about it. Interviews were mysteriously cancelled, venues where we were supposed to shoot were shut down by police, and our local Chinese staff were told not to help us report.

Tiananmen Square survivor won’t let China f... 03:14

At dawn Wednesday, China's national flag was raised over Tiananmen Square, as it is every day. But, on this anniversary, extra security forces -- some with machine guns -- held positions around the iconic plaza.

Just trying to report on the story, we found citizens serving as plain-clothed informants, eager to try and block our work and quick to get on the phone and relay our activity to authorities.

Moments later, police arrived to shoo us away. China was revealing its authoritarian side.

Twenty-five years ago, tanks rolled into Tiananmen Square to suppress a weeks-long student uprising that had spread across China with its demand for democratic reform.

The communist government's crackdown turned bloody. It's still not known how many died, but estimates range from 200 to more than 1,000 people.

"As a student here in China, do you learn about Tiananmen Square in the history books," Doane asked a pair of young Chinese college students.

"Not mentioned," they both agreed.

The students, whom CBS News won't name because they took a risk just talking to us, acknowledged it is difficult to find information about what the government generically refers to as the "June 4th incident."

"It's 25 years past, and we still don't know what happened," said the young woman who spoke to Doane. "I think that's... that's not cool, I think."

"Everyone in China, we have rights to know the truth," she added. "After so many years passed, and we still don't know what happened."

Try searching "Tiananmen Square" on China's heavily-monitored internet, or even keywords like "June 4" or "6-4-89," and results are censored.

Armed police stand guard at Tiananmen Square in Beijing
Armed police stand guard at Tiananmen Square in Beijing, June 4, 2014. REUTERS

It's so difficult to talk openly about Tiananmen Square in China, that Doane and his team traveled to Hong Kong -- beyond the reach of mainland Chinese authorities - to try and get more insight into the events of that day in history.

In Hong Kong, in a small, 800-square-foot Tiananmen Square museum, former protester Lee Cheuk-Yan is fighting to tell the story of 1989.

Asked how he got around censors to publicize the museum in places like Beijing, Lee told us they had to get creative.

"They don't call it June 4th, because once you call it June 4th, it would be erased. So instead they call it the 5/35 -- meaning May 35th," explained Lee.

It's a clever trick, simply pretending the calendar month of May continued on to a 35th day, which in reality fell on the unmentionable date of June 4.

While the story of Tiananmen Square is getting front page coverage on many of the world's newspapers, you Doane said that in the Chinese press -- both in native languages and English -- there was barely a mention on Wednesday.