A dozen protesters arrested for blocking lanes on I-5 in Seattle

At least a dozen people have been arrested for protesting on Seattle's I-5 north collector-distributor road and causing major traffic delays Monday. 

Trooper Rick Johnson with Washington State Patrol said authorities had to close a highway entrance midday while the protesters lay on the road. The road was cleared by 2 p.m.

It's unclear what they were protesting on the freeway, but an MLK march happening on the Yesler Way overpass above prompted those marchers to stop on the overpass and protest as WSP made arrests. 

One of the protesters on the highway reportedly suffered a medical emergency. The 40-year-old woman was treated at the scene and taken to Harborview Medical Center in stable condition. 

Two vehicles were impounded.