Seattle Fire Department Fire Investigators determined that fireworks caused an early morning fire in the University District on Sunday. Firefighters responded to the 4200 block of 12 Avenue NE at approximately 12:30 am July 5. Fireworks ignited a mattress that was leaning up against a detached garage. The fire extended from the mattress to the garage to the vacant house next door. Four fire engines, two ladder trucks, a medic unit and an aid car responded to the fire, along with support units. The fire was quickly put out and there were no injuries. Damage caused by the fire was estimated at $65,000.