Watch: Beijing Blast Witness Helps Journalists, Gets Abducted by Plainclothes Agents Claiming to Be Family

After an explosion outside the U.S. Embassy in Beijing earlier today, Chinese authorities moved quickly to secure the scene.

But as news began to filter out of the capital, the dark side of China's security state became apparent. While state censors were busy purging information, images and video footage from the country's social media, plainclothes police abducted a woman who had spoken to foreign journalists.

The incident was documented by Becky Davis, a journalist working for Agence France-Presse. In a series of tweets, she reported how the security services swept in to grab the woman, who had been sharing images and information with journalists.

A huddle of reporters gathered around the woman, attracting the attention of police. Then, Davis explained, "I turn my back for sec and next thing I know the poor woman has been dragged across the street away from the journos by plainclothes men."

As the woman struggled with four men, reporters and photographers surrounded them. The plainclothes men said it was a family dispute, and one was heard telling the woman, "Get out of here quick. Dad's waiting for you at home" as he dragged her down the street.

The crowd grew, and as she was pulled toward a black car the woman could be heard shouting, "I do not know that man. I didn't do anything! I was just a bystander!" One man, who appeared to be directing the gang, told Davis, "This is a family matter" as the woman was heard screaming in the background.

Once the car had sped off, Davis asked nearby uniformed police what had happened. One apologetically told her, "I'm sorry, I'm enforcing the law." A second pleaded, "It's not convenient now for us to do interviews. We don't know. Please leave, there are too many people here."

The first uniformed officer later found Davis as she was leaving the site, asking what media outlet she worked for. When she refused to answer, he became threatening, warning, "I have control over your visa!"

A 26-year-old man was detained following the explosion, which occurred at around 1 p.m. local time (1 a.m. ET). The suspect was the only person injured by the blast, which Chinese authorities have attributed to a "firework device." Posts on Weibo, a popular Chinese social media platform, were rapidly censored and erased in the aftermath of the explosion.

Earlier today, a woman was detained in front of the embassy after reportedly covering herself in gasoline in what is believed to have been a failed self-immolation protest.