Federal authorities are investigating several suspicious packages filled with white powder and delivered to Alaska's congressional offices today.

The offices of Sen. Lisa Murkowski and Sen. Mark Begich in Fairbanks and the Anchorage office of Rep. Don Young all recieved the packages this afternoon, and all three offices were evacuated.

Anchorage police said the Federal Bureau of Investigation and hazardous material teams are investigating the powder sent to Young's office.

In Fairbanks, a spokeswoman for Begich said the aide who opened the package is under quarantine until the powder is fully tested.

A spokesman for Murkowski said the package sent to her office is also being examined by the FBI and hazardous materials teams, but all staff members are safe and resuming work.

"Federal protective services found a suspicious package earlier this afternoon in the Senator's Fairbanks office, with an Arizona address," said Matt Felling. "They've already taken the package in for examination."

The package sent to Begich's and Young's offices also bore Arizona postmarks.

UPDATE: A representative for Young said test results revealed the powder sent to his office was a mixture of concrete, and also had an Arizona postmark.