The blaze started around 4:05 a.m. on the 1000 block of North Delaware Avenue.
Glenn Colville happened to be in the area and captured video of the fire on his phone.
"That was my first thought. I was like, 'I might as well get it on film,'" he said.
Officials say the two-alarm fire began on the third floor of the building and spread to upper floors.
"The embers were just floating everywhere. It was just raining pretty much wooden fire," said Colville.
Another viewer sent Action News drone video showing a bird's eye view of the fire damage. Crews were able to douse the flames before they consumed the entire building.
The Action Cam on the scene showed fire crews dousing the building with water to put out any hot spots that remained.
"They were huge, the flames were like shooting 20 feet high at least," Colville said.
In less than an hour, crews had the fire under control and worked to put out hot spots.
Fire investigators wouldn't confirm it, but some residents say people were living in the vacant building.
"I think there is people living in there, and I said probably one of them nodded off or something and fell asleep with a cigarette," Colville said.
The fire department says two people had to be transported to the hospital, adding that their injuries were not serious.
The cause of the fire remains under investigation.
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