The city police announced this on their Twitter page.
"Update: The suspect has been taken into custody," the statement said.
UPDATE: Suspect in custody
Officials from @CapitolPolice, with the assistance of MPD and @ATFWashington, provide an update regarding the active bomb threat situation near the Library of Congress https://t.co/qbewOH2jsy
- DC Police Department (@DCPoliceDept) August 19, 2021
Earlier, Capitol police warned of the threat of an explosion at the US Library of Congress.