CONCORD, Calif. (KGO) -- Last month's huge construction fire in Concord was intentionally set. That's according to the Bureau of Alcohol, Tobacco and Firearms, which also released surveillance video of an arson suspect recorded just moments before flames began shooting out of the building on Concord Blvd.
VIDEO: ATF releases surveillance footage of Concord arson fire suspect
The video starts with a man walking along a fence. Seconds later, he's hopping the fence and ducks under plastic sheeting with what appears to be a bag in his hand.
About a minute later, the suspect re-emerges. The bag is gone, but there are flashes of light coming from behind him as he quickly jumps over the fence and runs away.
RELATED: Crews to demolish Concord building under construction destroyed by fire
"I couldn't believe what I seen man, it's really scary," said Tim Nicholas, who, along with his family, were among 250 residents of the neighboring Renaissance Square apartments evacuated in the middle of the night as flames ripped through the construction site next door.
"I have grandkids with me. I think twice at night before I go to bed," said Nicholas. "Really it's scary. Knowing there are people out there doing stuff like this. It's crazy you know."
Now the Bureau of Alcohol, Tobacco, Firearms and Explosives is offering a $25,000 reward for information leading to the arrest and conviction of the suspect seen in the video.
RELATED: 250 evacuated, 2 injured in 3-alarm Concord fire
"The way he jumps the fence, it looks like he's been trained," said Reyes Ramos, who owns the Agave restaurant near the fire. His business was closed for a week. "I just hope for everything to get rebuilt as soon as possible and try to get everything back to normal."
No one was seriously injured but the 3-alarm fire caused an estimated $55 million in damage.