The FBI is on a manhunt for this 42-year-old man, pictured at right, Ryan Kelly Chamberlain II, whose San Francisco apartment was found to have explosives and bomb-making material in it on Saturday. As ABC 7 reports, he's considered armed and dangerous and could be driving around a Nissan Altima filled with explosives.

It's unclear how Chamberlain came to the FBI's attention, but they arrived at his Russian Hill apartment Saturday with a search warrant, only to find him gone. They searched the apartment near Jackson and Polk as part of a federal criminal investigation, and men in hazmat suits removed multiple objects from the premises, including a toolbox that they feared was a bomb. At some point, a "device" in the apartment was safely detonated, and neighbors said they heard a loud bang.

Early reports suggested that there may have been ricin, a deadly poison, in the apartment, but those reports seem to have been unfounded.

Chamberlain is on the loose and the public is being asked to be on the lookout, but not to go near him if you do happen to see him. What to look for:

Chamberlain is described as a white man with brown hair and blue eyes who is 6 feet 3 inches tall and weighs about 225 pounds. He was last seen wearing a navy blue hooded sweatshirt and jeans and driving a white 2008 Nissan Altima with either California or Texas license plates 7FQY085 and BX9M042 respectively.

This appears to be his Facebook, and by all accounts he looks like a totally normal guy who goes to Off the Grid and posts things about GlassHoles. This is how he describes himself in his profile:

Communications hack. Social-Media-ist since "social" was over here and "media" was over there. SF political junkie and oft-times operative. Save-the-world type. Early-adopter geek wannabe. Cheerleader for running and pro-cycling. Mouthpiece for movie-music. Starter-upper. Die-hard Giant.

Tips can be submitted to the FBI here, or by phone at 415-553-7400.

Update: The Chronicle has delved further into Chamberlain's story, and it turns out that he was well known in public relations circles around town. He lost a job in November working for Project Sport, and friends say he had gotten a little "weird" and introverted since then. A friend said to the AP, "I've never seen him be violent, ever, but I would definitely say that maybe emotionally and mentally he was a little unstable." This is his Twitter, and as you can see he was tweeting just on Friday, joking about the Hidden Cash Guy. [Chron]

Update 2: He posted a suicide note online, which published Monday morning. However he also tweeted this same morning, so it seems he's still alive.

[ABC 7]
[CBS 5]