UPDATE: Roanoke County multi-vehicle wreck leads to 10 miles of delays, lane closures on I-81 South

UPDATE 3:11 p.m.: The crash on I-81 South in Roanoke County is impacting school bus schedules at Andrew Lewis Middle School and Salem High School.
The wreck is causing considerable traffic congestion in Salem.
Salem City Schools say Andrew Lewis Middle School and Salem High School students who ride the bus are expected to arrive home later than usual.
UPDATE 3:06 p.m.: According to VDOT, only the southbound right lane and right shoulder are now closed at mile marker 138 on I-81 because of the Roanoke County multi-vehicle wreck, which has backed up southbound traffic for approximately 10 miles.

Meanwhile, northbound traffic is still delayed until at least mile marker 137, as seen on the 511 traffic cameras.

UPDATE 1:40 p.m.: VDOT says crews have reopened the northbound lanes on I-81 following the tractor-trailer crash in Roanoke County, but traffic cameras still show northbound traffic backed up four miles away from the crash.
Meanwhile, even though VDOT is reporting a three mile delay on I-81 South, traffic cameras show southbound traffic at a standstill five miles away from the scene.

ROANOKE COUNTY, Va.  — A tractor-trailer crash in Roanoke County is causing some serious backups along I-81 North and South Thursday afternoon.
According to the Virginia Department of Transportation (VDOT), all southbound lanes, the northbound left lane, and the northbound left shoulder are closed at mile marker 138 on I-81.

While VDOT has not announced an official estimate of the delays at this time, the 511 online traffic map shows southbound traffic stalling at mile marker 143 and bumper-to-bumper at mile marker 140, as well as northbound traffic piling up at mile marker 134.