A fallen tree and two motor vehicle accidents have severely snarled traffic on different stretches of Interstate 95 in Northern Virginia, affecting commuters in both directions, officials said.

There is a 20-mile backup on I-95/395 North in the Alexandria area, after a tree fell on I-395 near King Street.

On I-95 South in Prince William County, two accidents have slowed traffic to a near crawl.

One wreck, involving a tractor-trailer, is blocking lanes on I-95 South near the Dale City exit. There is debris from the tractor-trailer on the roadway. Cars are passing, but very slowly.

South of the tractor-trailer accident, near the I-95 South weigh station, there is an overturned car blocking the left side of the roadway. Again, traffic is moving very slowly in the area.

In the District, emergency crews are responding to an overturned vehicle at 16th Street and Northgate Road in Northwest. The two-car accident will impact traffic in the area.

For the latest traffic conditions, see our traffic map.