It's being called one of the largest manhunts in the Bay Area.
The FBI is looking for a man who they say was found to have a large stash of explosives at his San Francisco home.
Investigators are looking for 42-year-old Ryan Chamberlain.
The FBI considers him armed and dangerous after a large amount of what appears to be the poison, ricin, was found in his Russian Hill apartment.
Police say Chamberlain could be driving a white Nissan Altima with Texas plates.
They are concerned that the car could be rigged with some form improvised explosive device or a bio-chemical weapon.
On Saturday, agents spent the day in hazmat gear trying to contain the site at his apartment.
Chamberlain describes himself as a political junkie and sometime operative.
Although police say he has not made any threats, they do urge people to stay away from him and call 911 if you see him.