Another letter on its way to the nation’s has tested positive for ricin, ABC News reported a few minutes ago — this time on its way to the White House.  The discovery follows a flagged letter sent to Senator Roger Wicker found yesterday, and which is still the subject of testing:

ABC7’s Brad Bell reports that the letter was discovered at a postal facility at 3601 Pennsy Drive in Hyattsville. Hazardous materials teams could be seen and the facility is on lockdown, he reports.

This would be the second letter containing ricin that has been intercepted in the past day. On Tuesday, an off-site mail facility intercepted a piece of mail addressed to Sen. Roger Wicker, R-Miss., that tested positive for the dangerous substance.

Sources tell ABC 7 News that tests conducted on the letter meant for Wicker at Fort Detrick tested positive for ricin.

While writing this post, Twitter reports on a warning of a suspicious package in the Russell Senate Building began erupting:

We’ll have more on both stories as developments unfold.

Update: CNN reports that the Hart building is also being partially evacuated:

And a word of caution, too:

Good to keep in mind with reports of “suspicious packages,” too.

Update: Politico reports that the bomb squad has been called to both Russell and Hart buildings:

Update: Screencap of e-mail alert from Pittsburgh Tribune-Reviews’ Salena Zito:

Update: Was the package in Senator Shelby’s office?

Update: It’s not just Capitol Hill, either.  In Detroit, a local news report says that Carl Levin’s Saginaw office had to be evacuated because of a suspicious letter:

U.S. Senator Carl Levin’s Saginaw office was evacuated Wednesday morning after one of his staff members found what he considered a suspicious letter.

A hazardous material team was called to the scene around 11:30 a.m. to the office at 515 N. Washington in Saginaw. The building was immediately evacuated. The officer worker who found the letter was transported to a local hospital where he is undergoing a medical evaluation.

We’ll pray that he’s all right.

Update: CNN’s home page has this headline: “Capitol Police questioning man after sealed envelopes found in his backpack, sources tell CNN. ” No link to a story yet, but keep your eyes peeled.

Update: CNN’s story has been updated to include the backpack story, but it’s apparently not a good lead:

Shortly after that announcement, Capitol Police were checking out reports of suspicious packages or letters in two Senate office buildings. The first floor of the Hart Senate Office Building was evacuated shortly before noon, and police were questioning a man with a backpack in the area.

The man raised suspicion with the content of his backpack and how he responded to police questions, two Capitol Hill police officers said. The backpack contained sealed envelopes and was being x-rayed, one of the officers said.

A federal law enforcement official told CNN that authorities do not believe the man was connected to the letters found Tuesday.

Update: Roll Call says three suspicious packages set off the alerts:

U.S. Capitol Police are investigating several suspicious packages in the Hart and Russell Senate Office buildings, sources confirmed.

Loudspeaker alerts announced the discovery of packages on the first and third floors of Hart, while an email to the Senate community notified offices that police have responded to “a suspicious envelope on the third floor of the Russell Senate Office Building.” The email directed “all staff and other personnel” to “avoid this area until further notice.” Other news organizations have reported that the suspicious envelope was found in the office of Sen. Richard C. Shelby, R-Ala.

CQ Roll Call has confirmed that at least one of the suspicious packages in Hart was also an envelope.

Staffers in both buildings have been asked to shelter in place.

Update: Jeff Flake’s office in Phoenix also has a “suspicious letter“:

A suspicious letter has been found Wednesday at the office of Sen. Jeff Flake (R-Ariz.). Phoenix Police are investigating.

Flake’s office is near 22nd Street and Camelback Road.

This will be the fifth suspicious letter or package sent to U.S. politicians, including President Barack Obama, around the country in two days.

Update: The Washington Post reports that Capitol Police have reopened the Senate buildings after removing the suspicious packages:

First-floor offices in the building were evacuated, and people on higher floors were told to stay in their offices.

Authorities later reopened the Hart atrium, without immediately disclosing what — if anything — had been found.