OKLAHOMA CITY - Oklahoma City Fire Deputy Chief Marc Woodard says Monday's massive fire in Northwest Oklahoma City at NW 10th and Vermont is being treated as suspicious.

There were three firefighters who fell when the second-story fire at the old Hobby Lobby building collapsed to the ground floor. They are expected to be okay.

Chief Woodard was on scene and saw his own firefighter son, Bo, fall in the fire.

No one at home knew. Fire Chief Marc Woodard gave us the facts and focused on the fire at hand, just like he's done for 27 years now.

"Little nervous for me being on the scene I had just turned around and saw him there," Deputy Chief Marc Woodard said.

Woodard saw his son, 21-year-old Bo, fighting the flames from the second floor, when a "May-day" call went out that firefighters were down.

"Immediately, you know it's a collapse. It turned around and thought 'oh my goodness,'" Woodard said.

Then he saw his son through the smoke and debris.

"It was reassuring I made eye-contact with him and seeing he was ok, that was a comfort," he said. "They said, ‘we see him, we've got him, we can get him out quick.'"

Thoughts and fears turned immediately to the rest of the firefighter families and the two that fell alongside his son.

"Concerns for all the firefighters and just wanted to make sure they're all taken care of and very fortunate no one was under to get hurt there," Chief Woodard said.

Crews are investigating whether arson is to blame.

"I said 'son, I'm glad you're alright.' I told him next to the fire tactics, building construction's probably the best thing you can know in fire service this just resonates with that," Chief Woodard said. "Very proud of him, outstanding young men and I'm very proud of him."

The Oklahoma City Fire department family is thankful everyone made it out.

Wednesday on News 9 This Morning, we will do a live interview with all three firefighters. Find out what they're saying about this close call.