6:25 AM: SFD has a “full response” on scene in the 3400 block of 37th SW (vicinity map). Updates to come.

6:30 AM: Thanks to William for the photo above. He says this is an apartment building and firefighters pulled out a “burning mattress.”

6:50 AM: The response is down to a few units. We have a crew there checking on extent of damage and whether anyone was hurt.

(WSB photos from here)

7 AM: SFD tells us damage was confined mostly to the bed, and that no one was hurt.

ADDED THURSDAY: SFD tells us the fire’s cause was ruled “undetermined.”