The Canadian embassy on Pennsylvania Avenue in Northwest was given the all-clear after it had been evacuated as police investigated a suspicious package in the area.
The Washington Post reports the suspicious package is a letter that contained a suspicious substance.
Pennsylvania Avenue from the 400 block to the 600 block is ordered closed in both directions, between 4th and 6th streets.
Metropolitan Police Department spokesman Araz Alali says police were called at about 9 a.m. and gave the all-clear at approximately 10: 45.
Alali says no harmful materials were found, but the Secret Service is investigating.
Streets were shut down in the area on Friday morning but all have since reopened. It was not immediately clear what substance the letter contained.