Investigators have begun the meticulous process of trying to figure out what started a huge fire at west Windsor plastics recycling plant.

Representatives from the Office of the Ontario Fire Marshal, Windsor police and Windsor fire went to Sprucewood Industries Wednesday to probe the massive blaze that caused an estimated $1 million in damage.

“They are going to try to determine the area of origin and then they are going to work from there," says Lee Tome, Windsor’s chief fire prevention officer.

Thick black smoke and potentially toxic fumes billowed from the 700 block of Sprucewood Avenue for several hours Tuesday afternoon.

The fire broke out just after 3 p.m. The plant was occupied at the time, but no one inside was injured. A Windsor firefighter was taken to hospital with heat-related injuries, but was released.

The line of smoke in the sky could be seen from as far away as Leamington.

“It was wild,” says onlooker Larry Greco. “I could see it while I was on Lauzon. It felt like it was right in front of me."

Fire officials declared the fire out around 3 a.m. Wednesday morning.

The owner, too distraught to go on camera, told CTV News he's had the business for 17 years. Now there is nothing left.

“There's upwards of 120,000 pounds of plastics stored on site and at one point 75 per cent of it was burning," says Steve Laforet, Windsor’s deputy fire chief.

Fire officials say they had been on site to inspect the plastic recycling plant in the past.

"Our last inspection was in 2008,” says Tome. “There were some violations that were quickly corrected."

The City of Windsor issued a state of emergency Tuesday night and residents within a 1.5-kilometre radius of the fire were asked to stay in their homes. It was lifted by 10:30 p.m. Officials say air quality is no longer a concern.