If you're on the Red Line now or reading from the office, here are some buses providing detours and bus bridges:
From @metroopensdoors:
Metrobus F1 and F2 run between Takoma and Cheverly
Metrobus 52, 54 runs between L'Enfant Plaza and Takoma, 53 from Takoma to Mcpherson Square, 62 from Takoma to Georgia Ave Petworth
Metrobus G8 runs between Brookland and Farragut Square, H2 runs between Brookland and Van Ness, H4 runs between Brookland and Tenleytown
Metrobus K2 runs between Ft. Totten and Takoma
Metrobus R3 runs between Ft. Totten and PG Plaza
Metrobus E2, E3, E4 run between Ft. Totten and Friendship Heights
Metrobus 64 runs between Ft. Totten and Federal Triangle
Metrobus Q2 runs between Shady Grove and Wheaton and Silver Spring
Metrobus 60 runs between Ft. Totten and Georgia Ave Petworth
Metrobus J1 runs between Medical Center and Silver Spring
Metrobus 80 travels between Brookland and Fort Totten
Customers traveling to Silver Spring can take Metrobus 79 from Georgia Ave Petworth station on the Green line
More on MARC, from @metroopensdoors:
MARC operations stopped beginning with Marc 893, holding outside of Washington. Marc 879 and following trains will hold in Union Station.
Unsuck DC Metro reports on Twitter that riders can exit stations for a refund.