The incident was caught on camera by Jarrett Robinson.
It's one of an array of videos and images that emerged showing some police posing with protesters, but many more of officers being brutalized or humiliated by pro-Trump activists.
In the video, the officer - who police have not ifentified - can be seen as he's dragged and carried down the steps.
Finally, he's lifted up off the ground, only to have one protester pop out of the crowd to strike him on the head.
The video ends with protesters apparently escorting the officer away from the melee.
The protesters marched on the Capitol after attending a rally featuring President Donald Trump, who wrapped up his speech by calling on them to "march to the Capitol."
The crowd quickly overwhelmed law enforcement marched into the Capitol building after Congress convened to count the Electoral College votes that made President-Elect Joe Biden’s victory official – a result the president has maintained is fraudulent.
The FBI and other law enforcement agencies have made dozens of arrests since the riot that enveloped the Capitol building.
FOX 5 has reached out to D.C. police regarding the officer's condition following the incident.