Get out of your bubble. The cop's name was Brian D. Sicknick, and he died from injuries sustained fighting the rioters.

https://www.npr.org/sections/congress-electoral-college-tall...

According to Capitol police, the rioters "actively attacked United States Capitol Police Officers and other uniformed law enforcement officers with metal pipes, discharged chemical irritants, and took up other weapons against our officers."

https://www.uscp.gov/media-center/press-releases/statement-s...