iStock/Thinkstock(WASHINGTON) — A Washington state man has been taken into custody after suspicious packages were found at military bases and CIA headquarters in the Washington, D.C. area, according to the FBI, and officials said it’s possible other packages were mailed to additional mail processing facilities in or near the nation’s capital.Thanh Cong Phan, 43, was arrested at his residence in Everett, Wash., Monday by the FBI Seattle’s office and the Snohomish County Sheriff’s Office. Phan is scheduled to make an initial court appearance Tuesday afternoon in the Western District of Washington, the FBI said.An investigation determined Phan appeared to have sent the packages, which contained potential destructive devices, from the Seattle area to mail processing facilities at military bases and CIA headquarters in Langley, Va., the FBI said.A source familiar with the case tells ABC News that at least one of the suspicious packages sent to the military and government facilities included a long, rambling and largely unintelligible message, printed out on white paper. The message makes multiple references to “synaptic frequency” and President Donald Trump, a source familiar with the case tells ABC News.At one point the note reads: “President Trump business man we want $250 million all you dead,” the source said.Phan was previously known to the Secret Service, after sending letters to the White House, sources also told ABC News.Each package was collected for further analysis at the FBI lab at Quantico, Va., and at least one contained explosive material, the agency said.Officials at Fort Belvoir in suburban Virginia confirmed to ABC News Monday night that a suspicious package was found there that afternoon, and was contained and rendered safe.Michael Howard, an Army spokesman, confirmed reports that one of the suspicious packages was sent to National Defense University at Fort McNair around 8:30 a.m. Monday.That package contained explosive material, testing positive for black powder and residue. An X-ray indicated a suspected GPS and an expedient fuse attached. The package was eventually rendered safe and no injuries were reported, he said.The FBI, Secret Service, and hazardous material and explosive ordnance disposal units responded to the scene, Howard said. The FBI is the lead law enforcement agency investigating, Howard added.ABC News confirmed Tuesday that in addition to Fort McNair and Fort Belvoir, Joint Base Anacostia-Bolling in southeast Washington also received a suspicious package Monday. The Naval Surface Warfare Center in Dahlgren, Va. also received a package, the FBI said.“We are tracking the delivery of suspicious packages to multiple military installations in the National Capital Region,” a Department of Defense spokesperson said in a statement. “This incident is currently under investigation and we refer all queries to the Federal Bureau of Investigation.”An FBI statement says the joint investigation with the U.S. Postal Inspection Service is ongoing, and it is possible that more packages were mailed to additional mail processing facilities in the Washington, D.C. metropolitan area.Copyright © 2018, ABC Radio. All rights reserved.