Update:  Investigators have determined that a fire inside a motorhome in Lake City was intentionally set. The one in the University District was not.

Although at least five other fires have been set recently near the scene of last night's University District blaze, the fire department has ruled last night's incident—in which several mattresses were set on fire—as "accidental." The fire apparently started when someone flicked a cigarette into an enclosed area where the mattresses were stored.

Fire crews in the University District called for police assistance tonight  at a blaze in the 4100 block of 12th Av Ne.

By our count, there have been at least five fires set near the scene of this latest incident in the University District.

Medics transported one man from the scene to Harborview, and police followed. It's not clear whether the man is suspected of starting the fire, or was simply injured during the incident.

One neighbor we've emailed with has theorized that a man living in the area may have been responsible for the recent fires, and says tonight's fire began when someone torched a mattress left outdoors.

Fire crews were also asking for a member of SPD's arson/bomb squad to be dispatched to a trailer fire at NE 143rd and 17th Ave NE.

More tomorrow.

Thanks to Silver and John.