The declaration came a day after authorities said they plan to burn down the home next week because it is the only way to eliminate the danger from nine to 12 pounds of highly explosive materials found inside.
The state will set up protective barriers around the site, and dozens of homes in the neighborhood will be evacuated for at least a few hours during the procedure.
According to a search warrant, items seized from the house included sulfuric acid, nitric acid and hydrochloric acid.
Authorities also confiscated a grenade mold, a bag with pieces of metal, a jar with ball bearings and three wireless doorbells with remotes. Two handguns, a .22-caliber Ruger and a Glock 19, also were taken, along with a blue Escondido police shirt.
Investigators also confiscated three computers, a book on high explosives, two molds of human faces and four wigs.
The home owner, George Jakubec, pleaded not guilty to 26 counts of manufacturing explosives and two counts of bank robbery.
There is still no word on why he was stockpiling highly volatile explosives.
Jakubec remained jailed on $5.1 million bail.
The Associated Press Contributed to this report.