Actors Jorja Fox and George Eads, who play investigators Sara Sidle and Nick Stokes, were fired after asking for more money to stay on the show, according to the reports.
When Eads didn't show up to work Thursday, the first day of production for the next season, and Fox didn't provide the network enough assurance that she would return to work, both were let go, reported KCBS.
A CBS spokesman said the network had no comment.
The actors were in the fifth of their seven-year contracts.
Though a search was under way for their replacements, it's unclear whether show creators will recast the characters or develop new ones, the reports said.
The show picked up four Emmy nominations Thursday, including one for best drama series.
Eads and Fox are hardly the first television series actors who held out for more money and instead were given their walking papers. Suzanne Somers demanded more money at the beginning of the fifth season of "Three's Company" in 1981; the show continued for three more years without her.