Fire officials said the apartment was surrounded by SWAT teams, and sheriff's officials said lateThursday they didn't know if a gunman inside was dead or alive, The Modesto Bee reported.
"We're not sure at this point what actions he's taken and what he might be doing," Sgt. Anthony Bejaran told KCRA-TV, Sacramento.
Battalion Chief Hugo Patino posted on his Twitter page: "Fire on Chrysler continues to burn. Structural collapse occurring. Fire crews doing a good job of protecting the exposures."
The slain deputy was identified as Robert Paris, the Bee reported. The names of the other victim and the person inside the dwelling weren't released.
The shootings occurred about 11 a.m. Thursday when the deputy and second man were trying to serve an eviction notice at an apartment complex.
An unidentified man who lives nearby told the newspaper the deputy and the man with him apparently were drilling through the lock on the apartment door when the suspect fired at them from inside.
Dozens of neighbors were evacuated from the area.