Shortly before a three-alarm fire broke out in a northeast Minneapolis lumberyard late Saturday, two people were captured on surveillance video sneaking into the complex. One of the figures appeared to enter a large building minutes before smoke began wafting from the structure.

The suspect is seen walking in and out of the building at Shaw-Stewart Lumber, 645 NE. Johnson St., several times, before fleeing on foot.

The grainy security footage and other evidence point to the blaze being intentionally set, Minneapolis authorities said on Wednesday, as they continued searching for the suspected arsonists.

It took about 35 firefighters nearly four hours to put out the fire, which eventually spread to a nearby shed, authorities said. The fire likely started in a dumpster in the burned-out building, they said.

Arson investigators believe that alcohol was a contributing factor, after finding shards of a broken vodka bottle they say was used to smash the front window of the building's showroom, said police Sgt. Sean McKenna.

Authorities said it was too soon for a damage estimate.