Cause of business fire in NW Grand Rapids 'undetermined' Copyright by WOODTV - All rights reserved Smoke rises from a fire in northwest Grand Rapids. (July 1, 2015) [ + - ] Video

24 Hour News 8 web staff -

GRAND RAPIDS, Mich. (WOOD) -- The cause of a large fire that destroyed part of a Grand Rapids demolition and salvage business Wednesday night is still unknown and will be difficult to determine, according the Grand Rapids Fire Department.

A news conference was held Thursday afternoon to provide updates on the investigation at the Pitsch Companies property. Grand Rapids fire investigators said they will be returning on Monday to continue their investigation on the $1 million loss.

Fire officials said challenges they faced in determining a cause included the amount of heavy metal wreckage in the collapsed building, which must be moved.

Not a lot of combustibles are believed to have been near where the fire started, and two truck drivers who returned to the building before the fire started reported nothing out of the ordinary. The fire inspector also said it didn't appear any building codes had been violated.

The fire sparked around 9:30 p.m. at one of the seven buildings at the Pitsch Companies property located at 675 Richmond St. NW east of Alpine Avenue. A large plume of thick, black smoke could be seen rising from the blaze from across the city. Witnesses reported hearing explosions that authorities said were caused by oxygen, propane and acetylene tanks in the structure.

Police were on the scene within three minutes of the fire 911 call and confirmed the fire. Eleven of the Grand Rapids Fire Department's 17 crews responded.

Around 11 p.m., firefighters said the fire had been contained to the building of origin and was under control.

Firefighters were back at the business Thursday morning to put water on hot spots. Workers were also putting up fences around the rubble.

Pitch Fire Grand Rapids, MI clip 9 Day After from Adam Dabaja on Vimeo.

Residents in the area were advised to close their windows and stay in their homes to avoid breathing in the smoke, but authorities said the smoke plume did not contain hazardous materials. They said it was mostly wood products burning.

An evacuation was also ordered for areas off Richmond east of McReynolds Avenue for a time, but was soon lifted.

Storm Team 8 said the thick plume of smoke rising from the fire was visible on radar.

Industrial fire on the northwest side of Grand Rapids from Adam Dabaja on Vimeo.

Pitsch's website says it is involved in demolition, environmental services, salvage, portable toilets, dumpster services, sanitary landfill, transfer station, land development, and concrete crushing.

The business was closed when the fire broke out and no one was there at the time, firefighters said. There were not any reports of injuries.

Pitsch Companies owner Lewis Pitsch told 24 Hour News 8 over the phone late Wednesday night that he was relieved no one had been hurt.

He said the building that went up in flames is the shop for the maintenance department. He said he estimates the fire caused about $1 million in damages, including the building and equipment inside. Among that equipment was at least $100,00 in brand new semi-truck tires. He knows insurance will cover the building, but was unsure about the equipment.

Pitsch said he plans to rebuild. In the meantime, the company also owns a building next door that the maintenance crew can use as a temporary shop.

He thanked fire crews for saving nearby buildings and equipment. He said firefighters did a great job and prevented a lot of other possible damage.

The cause of the fire is not yet known.

Cause of business fire in NW Grand Rapids 'undetermined' Gallery 1 Smoke rises from a fire in northwest Grand Rapids. (July 1, 2015) Smoke rises from a fire in northwest Grand Rapids. (July 1, 2015) Smoke rises from a fire in northwest Grand Rapids. (July 1, 2015) Flames at a fire in northwest Grand Rapids. (July 1, 2015) Crews dump water on the fire at Pitsch Avenue NW around 10 p.m. (July 1, 2015) Crews dump water on the fire at Pitsch Avenue NW around 10 p.m. (July 1, 2015)

--24 Hour News 8's Heather Walker and Evan Dean contributed to this report.