BURLINGTON, Wash. — Authorities say a crash on Interstate 5 north of Seattle near Burlington killed one person and shut down all northbound lanes of traffic.

Washington State Patrol trooper H. Axtman said on Twitter the crash happened Friday evening just north of Burlington near Bow Hill Road.

Axtman says the motorist who caused the crash was driving south and crossed a grass median, hitting a northbound box truck head-on. She says it’s unknown why the driver crossed the median.

The Washington Department of Transportation said on Twitter at about 6:25 p.m. Friday that northbound traffic on the interstate in the area was backed up for nearly six miles.

No further information was immediately released.