(CNN)It's a viscerally emotive picture. A woman who appears to be pregnant lies on the floor of a subway station. It was taken on July 21, after a mob attack in the Yuen Long district of Hong Kong left at least 45 people injured -- including the woman, a civilian who had been caught up in the attack and became known locally as "the woman in white" or "big belly lady," slang for "pregnant lady" in Cantonese.
Hong Kong isn't just battling on the streets: There is also a war on misinformation online
On social media, posts alleging that she had suffered a miscarriage were shared thousands of times. As more footage emerged, public outrage intensified over the Yuen Long violence, and towards the police for their alleged failure to protect victims from the baton-wielding attackers, who appeared to target protesters returning home from a march.
But then came the counternarrative. She wasn't pregnant, people claimed, and her alleged miscarriage was a politically motivated rumor.
Though local media claim to have confirmed her pregnancy and the safety of the baby, the truth remains contested. Either way, the incident clearly illustrates the power of unverified online rumors to shape the narrative driving the city's worst political crisis in decades.
Mass protests began more than two months ago over a controversial bill which would allow residents to be extradited to face trial in mainland China. The bill has since been shelved, but the uproar stoked a wider civil unrest that shows no sign of abating.
On the streets, protesters and police face off each week with escalating violence. Online, an equally bitter battle is being waged using the weapon of misinformation.
Just like the protests and clashes, fake news is threatening Hong Kongers' unity and safety -- and there is no end to it in sight.
In Hong Kong, there's virtually no way to avoid misinformation.
In the subway, fake news is anonymously AirDropped onto commuters' phones. Rumors and speculation posted by both individuals and local blogs are plastered over Facebook, Twitter and Instagram, and shared on messaging apps such as WhatsApp and Telegram. Their controversial content is the topic of daily conversation citywide.
The rumors that take hold often prey on pre-existing fears and paranoia -- and are just believable enough to work.
"We all have a cognitive tendency to believe what we want to believe and dismiss what we don't want to believe, without any evidence that suggests what is true and what is not," said Masato Kajimoto, a journalism professor at Hong Kong University, who specializes in misinformation.
In one viral tweet, for example, an unverified user warned the Chinese military was about to cross the Hong Kong-Shenzhen border to wage a Tiananmen Square-style crackdown, with an accompanying video of tanks at a train station.
But a station sign in the video reads "Longyan" -- which is not in Shenzhen, and likely refers to a city in Fujian province, hundreds of miles away. Fact-checkers online pointed this out, but it was too late -- the video has now been viewed more than 848,000 times and has more than 8,000 retweets.
The tweet tapped into a powerful fear that underlies the ongoing political crisis -- that Beijing is encroaching on the unique freedoms of this semi-autonomous Chinese city. As a former British colony, Hong Kong enjoys protected freedoms of speech, press, and assembly, as decreed when Britain handed the city back to China in a model of governance called "one country, two systems."