The blaze that killed nine firefighters in a furniture store started on or near a loading dock, federal investigators confirmed Saturday, a day after the victims were mourned in a joint ceremony.

The Bureau of Alcohol, Tobacco, Firearms and Explosives (search) said investigators have completed their probe at the scene and will continue examining evidence for the cause of the blaze, which caused the single heaviest loss of firefighters since the Sept. 11 attacks.

The victims honored in a memorial service Friday were Capt. William "Billy" Hutchinson, 48; Capt. Mike Benke, 49; Capt. Louis Mulkey, 34; Mark Kelsey, 40; Bradford "Brad" Baity, 37; Michael French, 27; James "Earl" Drayton, 56; Brandon Thompson, 27; and Melvin Champaign, 46.

Click here to listen to the dramatic 911 call, reported by MyFoxDC.com

Click here to view photos of Friday's memorial service.