In a statement, the department said, "Nyx served alongside her human partners with unmatched dedication, fearlessly protecting our communities and upholding the values of law enforcement. Her legacy of courage and sacrifice will forever be remembered."
The group Friends of Rockford Police K-9 said Nyx was fatally shot while protecting her handler.
"The Friends of Rockford Police K-9 board members are shocked and saddened by this senseless act. Nyx was an amazing K9 officer and we have heavy hearts for her handler," said Kathy Hansen, president of the Friends of Rockford Police Board.