There wasn't, but the way it was originally reported was careless, and could easily be construed as a third person:
"Officers arrived at the house, knocked on the front door and were let inside by an unknown person. They discovered DePape and Pelosi struggling for a hammer, and after they instructed them to drop the weapon, Scott said, DePape took the hammer and “violently attacked” Pelosi."
https://web.archive.org/web/20221029222730/https://www.politico.com/news/2022/10/28/police-pelosi-attack-intentional-00064098