8:55 PM: Big emergency response on the northbound 1st Avenue South Bridge right now – originally dispatched as a “rescue extrication” but now being downsized. The traffic alert says this involves a collision toward the north end of the bridge. If you were headed that way, wait a while or try another route across the river.

9:04 PM: WSDOT says traffic is being diverted off the northbound bridge at Michigan, as the collision is just north of that exit. This was initially dispatched as a two-vehicle collision, with one reported to have flipped.

9:19 PM: We’ll follow up with SFD later but so far at least one person is reported injured, a woman believed to be in her 20s.

UPDATE FROM SFD: Four people were treated for injuries, according to SFD spokesperson David Cuerpo: A 26-year-old man, 44-year-old man, 60-year-old man, 20-year-old woman (who asked to be taken to a hospital), all stable.

(SPD photo)

ADDED THURSDAY AFTERNOON: SPD says today that the 26-year-old man – driver of the vehicle that flipped – was booked into jail for unlawful gun possession, after one was found in his car and he turned out to be a convicted felon.