MONTGOMERY COUNTY, Va. - UPDATE
Both lanes are now open and traffic is flowing again.
A crash is blocking a stretch of I-81 North in Montgomery County, causing a backup Friday morning.
All northbound lanes are closed at mile marker 120, which is close to the Route 11 Christiansburg exit.
There is a 2-mile backup, as of 6:15 a.m.
Emergency crews are on the scene.
Check back for updates.
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