A jack-knifed semi-truck is blocking the three left lanes of southbound Interstate 5 near Mounts Road.
The accident happened at 5:50 p.m. at milepost 116. Traffic is proceeding in the right lane. The current backup is about 8 miles.
WSP and WSDOT Incident Response are on scene. Tow is en route.
6:40 UPDATE: All lanes are now clear. The current backup is about 9 miles, to Bridgeport Way.