Most streets are back open in downtown D.C. after being closed for several hours on Monday. Police say a woman is now in custody after barricading herself in an office building in the 1900 block of K Street NW, which caused the major traffic backups. (WUSA9)

The latest:
• A 31-year-old Virginia woman is in custody after she barricaded herself inside an office building in the 1900 block of K Street NW.
• After being closed for several hours, streets in the area reopened.
• Police say a shot was fired about midnight, leading to the situation.

Updated at 5:07 p.m.

Authorities arrested 31-year-old Sophia Dalke of Springfield following Monday morning’s barricade incident. Dalke, who surrendered to police around 10:30 a.m., was charged with assault on a police officer while armed, according to a department press release.

Updated at 4:30 p.m.

All streets are now open, D.C. police said.

Updated at 12:10 p.m.

Most streets in downtown D.C. have started to reopen near an earlier barricade situation in the 1900 block of K Street NW. Police said the intersection of 19th and K streets NW was still closed at midday.

Around 10:30 a.m., D.C. police said a woman is in custody after she had barricaded herself inside an office building at 19th and K streets NW.

Lt. Sean Conboy, a D.C. police department spokesman, said the “situation has been peaceably resolved,” after the woman was taken into police custody. Her name was not released, and it was not clear whether she would be charged with anything.

Streets in the area were closed throughout the morning commute, creating a traffic mess for pedestrians and drivers. The situation began about midnight after shots were fired, police said.

No one was reported injured. Police would not release the exact address where the barricade situation unfolded, citing security concerns. Several blocks stretching along 19th Street NW, including L, K and M streets, were impacted. While many commuters complained about the large swath that was shut down at rush hour, police said it was done for security and safety reasons.

At 19th and I streets NW, workers waited Monday morning behind a police line to try to get into their offices.

Doris Garcia, 53, of Arlington, had been among those waiting to enter her building at 19th and K streets for two hours. She had arrived downtown at about 8 a.m. and thought it would be clear by 10 a.m., but it wasn’t.

“With the way things are happening nowadays, you can’t play it too safe,” she said. “Especially with what happened in Paris this weekend.”

Traffic was snarled, and Metro reported major bus delays throughout Monday morning’s rush hour.

Lt. Sean Conboy, a D.C. spokesman, said the shots were fired about 12:20 a.m. in that area. He described the situation as a “person in crisis.” Earlier in the morning, police had said the person was in a mental health crisis. Authorities said the situation was not terrorism related.

Drivers and pedestrians were advised to avoid the area as traffic sat almost at a standstill in parts of downtown.

Washington Post reporter Luz Lazo surveys the traffic around M Street and Connecticut Avenue NW, caused by a barricade situation in downtown D.C. Monday morning. (Luz Lazo/The Washington Post)

Updated at 9:06 a.m.

Just before 9 a.m., police said roads remained closed in the downtown D.C. area as they dealt with a barricade situation in an office building. Traffic in Dupont Circle remained backed up. It was not clear when the situation, which began about 1 a.m. Monday, would be resolved.

No injuries were reported.

https://twitter.com/stephaniethum/status/666256192331776000

Updated at 9 a.m.

Traffic was jammed at 15th and I streets NW in downtown D.C. on Monday morning as authorities continued to deal with a barricade situation in an office building. No one was reported injured, and police said that the situation was contained but that the person involved was not in custody.

The situation began about 1 a.m. and involved a person barricading herself inside an office building in the 1900 block of M Street NW. Several streets around that area were closed, causing a traffic backup and major delays for drivers, and, at times, pedestrians.

Streets in the area were closed, including 18th to 21st streets NW and M to I streets NW. It was not immediately clear how long the streets would stay closed, but police said they planned to start opening some of them.

Unrelated to the barricade situation, authorities said protesters were in the area of southbound 17th Street near Pennsylvania Avenue in Northwest Washington, and drivers should expect rolling road closures.

It was not immediately known what they are protesting.

Updated at 7:55 a.m.

Traffic snarled in part of downtown D.C. Monday  morning as police closed several streets in the area of 19th and M streets NW as they dealt with a barricade situation.

While streets were closed in the early morning hours, officials said they would gradually start to roll back the closures as the situation was considered contained, meaning that the person was isolated but not yet in custody as of 7:45 a.m. Police said the person involved in the barricade situation is believed to have a mental health crisis.

Earlier in the morning, streets were closed, including 18th to 21st streets NW and M to I streets NW. Some pedestrians were also saying they were unable to get through those areas, and many drivers reported lots of backups and few authorities out dealing with the traffic nightmares.

Some drivers reported moving only one block in two hours as they traveled along Connecticut Avenue NW. It was not immediately known when the situation would be resolved. Drivers are advised to avoid the area. Metro buses said they were also experiencing delays as a result of the ongoing situation.

D.C. Police said the situation is not related to terrorism.

Original post at 5:30 a.m.

D.C. Police said several downtown streets in Northwest are closed Monday morning as they are dealing with a situation in which a person  is barricaded inside an office building. Police said they do not  believe the situation is related to terrorism and there are no reported injuries.

Few details were immediately available, but authorities advised commuters to avoid driving in the area. The street closures include 18th to 21st streets NW and M through I NW.

At 7:30 a.m., police said the situation is contained but the person is not in custody. Some of the street closures were gradually being scaled back, but traffic nightmares remained for many commuters as they tried to get to their offices.

The incident began about 1 a.m. in the 1900 block of M Street NW.

Metro put out warnings on social media to its riders saying they should expect delays on certain routes that travel through that area. The delays would be in both directions of the lines.

It was not immediately clear how long the street closures would last.

Staff writers Peter Hermann, Luz Lazo and Martin Weil contributed to this report.