The Tulsa Fire Department said a truck caught fire and the flames spread to a large amount of wooden pallets at a business near 11th and Fulton.
Witnesses say they heard what sounded like explosions. When they looked outside, they saw the flames and smoke in the middle of the yard at Mill Plastics.
Several units including a ladder truck responded to the scene, and firefighters got the fire under control in just a few minutes. About 40 firefighters responded.
Investigators say it was likely caused by a cigarette.
The fire burned a few vehicles, wooden pallets, cardboard and some other equipment, but no employees were injured.
Many neighbors were standing on 11th Street watching the fire burn. Some said they saw employees running out to get away from the flames.
"I heard explosions, and I opened the door and the fire was contained then," said Sean Carpenter, a neighbor who shot cell phone video of the fire.
"In a matter of seconds, the whole thing went up in flames."
The fire burned for about 30 minutes.
"The flames were really building up, and one of the light poles caught on fire," said witness Frank Fitzgerald.
The business, Mill Plastics, has been the site of an industrial fire in the past, according to News On 6 reporter Emory Bryan.
We've learned one firefighter hurt his wrist while battling the fire, but he is expected to be OK.