From the inbox (thanks to “AA”):

Looks like either a glass truck lost its load, or someone t-boned it. There is glass ALL over the intersection and the police have a big blockade around it and a traffic arrow. The backup was almost a half-mile down Delridge when driving North to South. There is no backup driving South to North. Sylvan is blocked west of Delridge. The glass truck is parked in the Arco parking lot and there are people milling about. Worth letting people know if they can take an alternate route to the South Delridge area, it’s probably a good idea.