UPDATE 7:54 p.m.: Metro is responding to the major delays on Metrobus routes. But there's no timeline yet for when people at various bus stops will be picked up.
Snow and icy conditions forced Metro to shut down all Metrobus service at 9:30 p.m. Buses will finish their routes before heading back to garages.
A spokesman said Metro is aware of the delays throughout the region. Metro is sending services to stops. He said people will be picked up "as soon as possible."
UPDATE 6:30 p.m.: Metro reports the problems at the Dupont Circle and Federal Center SW stations were caused by arcing insulators.
Track workers were dispatched to inspecting the affected lines about 5:20 p.m.
Trains were single tracking on the Blue and Red lines.
UPDATE 5:42 p.m.: Check out the calamities that have befallen Metro in the midst of rush hour this evening:
There is smoke in the tunnels near Woodley Park on the Red Line and Federal Center SW on the Blue/Orange line.
Earlier, a switch malfunction at Largo on the Blue Line began causing delays. And even earlier on the Blue/Orange line, trains began single-tracking between Federal Center SW and Smithsonian due to another switch malfunction.
Metrobus has also announced its moving to snow emergency routes only throughout the region due to poor road conditions.
UPDATE 11:08 a.m.: An earlier problem outside Bethesda has been cleared, but delays continue in both directions.
UPDATE 10:24 a.m.: This just in, trains are sharing same track between Medical Center and Friendship Heights due to a track problem outside Bethesda. Delays in both directions.
UPDATE 10:05 a.m.: Metro's red line has significant delays, AP reports. A spokesman says a problem with a track insulator caused smoke Wednesday morning.
According to AP, the problem was discovered about 8:30 a.m. Crews are making repairs, but it's not clear when normal service will resume.
UPDATE 9:40 a.m.: The fire is under control, D.C. Fire reports. Firefighters are investigating. No injuries reported.
D.C. Fire is reporting that trains on the Red Line are single-tracking due to a fire along the track near Dupont Circle Metro Station. The cause of the fire is most likely due to an insulator, officials say.
D.C. Fire reports the incident is disrupting service between Woodley Park and Dupont Circle. Trains are sharing tracks between the Dupont Circle and Van Ness-UDC stations. Expect delays in both directions.