Updated at 4:16 p.m.
A few people who came in contact with the powder were quarantined inside the building for first responders to check them out, and about 20 other employees who work at the organization’s headquarters on New Jersey Avenue SE went to wait outside, Hooper said.
“We get threats every day,” mostly online or by phone, Hooper said. “We don’t always get substances in the mail.”
He said the volume of threats has increased lately, starting with the Paris attacks and then further after the San Bernardino attack and then Donald Trump’s call for a temporary ban on Muslims entering the United States.