http://kansascity.sbnation.com/kansas-city-chiefs/2011/9/4/2404865/kansas-city-chiefs-matt-cassel-reportedly-suffers-cracked-rib
Here's the tweet from Nick Wright, who appears to work for 610am in Kansas City:
Edit, another report:
http://www.rotoworld.com/headlines/nfl/211713/football-headlines?r=1