Riot police use tear gas against protesters on Sunday in a failed attempt to clear crowds demonstrating for voting rights outside government headquarters. (Associated Press)

BEIJING — Social media users in China gave a collective groan Monday after the country's Communist rulers blocked Instagram in the wake of protests in Hong Kong.

No more sepia-tinged phone pics of your latest meal in Shanghai or, perhaps more significant to Chinese censors' minds, no more shots of Hong Kong officers in riot gear unloading canisters of pepper spray and tear gas into the faces of Hong Kong's largely peaceful demonstrators.

Thousands remained on the streets in Hong Kong on Monday, protesting over Beijing's decision to reject calls for open nominations for the election of Hong Kong's chief executive in 2017. The protests escalated on Sunday, with riot police resorting to the use of tear gas. (The Washington Post)

Until Monday, Instagram was one of the few foreign social media apps left untouched, even as Facebook, Twitter and other services were blocked.

It has been the vehicle of choice for some dissident artists such as Ai Weiwei. And this weekend, it was a handy way for protesters laying peaceful siege to government headquarters in Hong Kong to send out visual documentation of police charging at protesters with batons and firing tear gas into crowded streets.

Early Monday Hong Kong protesters were gearing up for another day of pro-democracy protests. Many had spent the night sleeping on roads in the central business district. The unrest is the worst since China took back control of Hong Kong from Britain in 1997. (Reuters)

The protesters' clashes with police Sunday night and into the wee hours of Monday were accompanied by a barrage of hashtags: #hk, #hongkong, etc. #Occupycentral, a rallying cry for democracy activists of late, had 9,103 posts as of Monday afternoon. So when the service turned off within hours of protesters getting tear-gassed, many Instagram users assumed Monday that Chinese censors had decided it was not in their interest to let pictures circulate of Chinese residents standing up en masse to local authorities.

(SEE: Photos from Hong Kong protest.)

Hong Kong police used tear gas for the first time to break up pro-democracy protests on Sunday. Officials had warned that these protests were illegal. (Reuters)

The sudden loss of Instagram in China drew the ire of Chinese netizens, including some who weren't even aware of the protest before the shutdown.

"No one cared before what was happening over there in Hong Kong. We just wanted to quietly stalk our pop stars and get updates on ball games. But now that you've done this we have to care," posted one angry blogger named OhSoCute on a Chinese microblogging site.

"Once again, I feel that I am forced to wear a huge pair of eye patches," another poster sighed.

As of Monday, Instagram remained available in Hong Kong, which — because of its history as a British colony — enjoys freedoms that most cities in mainland China do not.

Chinese officials have tried curtailing Instagram before. This summer, it was abruptly removed from the Android app store in China.


Protesters clash with riot police  in Hong Kong. (Anthony Kwan/Getty Images)

(SEE: How China has blocked the internet through the years.) 

But the censorship of Instagram was just one of many ways that Chinese authorities attempted Monday to limit awareness in China of the protest in Hong Kong.

There were some signs that Hong Kong-related pictures on China's social media services such as weibo sites and WeChat were being deleted or blocked.

The news was similarly kept off the home pages of most Chinese news sites, which almost uniformly ran the same story distributed by the government-controlled Xinhua News Agency — a report that calls the protests "an illegal gathering."

An editorial by China's nationalistic, state-run Global Times blamed "radical activists" for ruining Hong Kong's image and accused foreign media of making unfair comparisons to the 1989 Tiananmen Square crackdown.

Soon after, Chinese versions of the editorial were deleted online (but the English version remained untouched as of Monday afternoon).

Liu Liu and Gu Jinglu contributed to this report.