Fire investigators have determined that the cause of the massive warehouse fire at the former Pa's Woodshed warehouse is arson.

The fire was reported last Wednesday night shortly before 10:30 p.m. and completely destroyed several buildings at the Montgomery Street site.

Officials say that multiples fires were set in four different buildings.  The investigation has now been turned over to arson detectives.

Cadaver dogs have been searching the site and fire officials say that there are several spots of interest and that the dogs will be returning on Wednesday.

The site was home to Pa's Woodshed, a furniture store and warehouse that was in business from the early 70's and closed in the 90's. The site is currently owned by LCP Demolition and Construction which had plans to develop the site.