( CNN ) -- The FBI is asking for the public 's help to find a San Francisco man accused of having explosive materials at his home . Ryan Kelly Chamberlain II , 42 , was last seen Saturday south of the city , the agency said in a statement . `` We do n't know the intent or motive yet , '' FBI agent Peter Lee told reporters , stressing there was no threat to public safety . Chamberlain was described as a white male , 6 feet , 3 inches tall , and 225 pounds , with brown hair and blue eyes . He was last seen driving a white 2008 Nissan Altima with either a California or Texas license plate . He should be considered armed and dangerous , the FBI said . Chamberlain 's block was closed for some 15 hours over the weekend as investigators searched and cleared the area , CNN affiliate KTVU reported . It was not immediately clear what led them to that site .
Ryan Kelly Chamberlain II Chamberlain II , Saturday , was last seen 42 south of Texas . He should be considered armed and dangerous , the CNN says . `` We do n't know the intent or motive yet , '' an agent tells reporters .