A building on the site near the former Thunderbird Motor Hotel in Arlington caught fire late Wednesday night.
Arthur Hammonds was at church next to the site the building quickly became engulfed in flames.
“Right in this corner right here, we saw small flames and about a minute later it caught that tree," he said. "And just went high, all the way across."
Firefighters were back at the scene surveying the damage Thursday.
The state fire marshal who has taken over the investigation said they don’t know what caused the fire.
A source from Jacksonville Fire and Rescue said the fire is deemed suspicious because of the fact that it was able to get so massive so quickly in a vacant building.