Fire investigators are working to determine what caused a massive fire in the Leduc industrial park Thursday afternoon.

The fire started at about 4:30 p.m. Thursday in the Global Fusion facility, a business that coats pipes for the oil and gas industry.

A witness said the fire appeared to spread inside the building very quickly.

“The big door over there, that’s really black – we could see a little bit of flame in there,” Witness Bryce Fulton said. “Then it wasn’t two minutes later, and it was engulfed in smoke, you could barely see the building.”

Firefighters from three jurisdictions were called to the scene – at one point, about 40 firefighters were on the scene battling the flames.

Crews arrived to find smoke and flames pouring from the warehouse.

At first, there were concerns battling the blaze as it wasn’t clear what types of chemicals were inside the building at the time – however, the fire chief determined any chemicals had little impact on air quality in the area.

A manager with the company said the fire started during a shift change – and everyone inside, about 30 employees, got out safely.

“They were pretty shaken up, I talked to our project coordinator, he did a great job in getting the guys out on time,” Kyuin Shim said. “Good thing we had some processes in place, they got out of the facility as quickly as possible.”

Fire crews stayed on the scene through the night, putting out hot spots.

CTV News has learned investigators were on the scene Friday morning, a damage estimate has yet to be determined.