Authorities investigating explosion in Lombard

Authorities continued their investigation Tuesday into an explosion that injured a man and damaged a commercial building in Lombard.

Firefighters responded at 9:12 p.m. Monday to a report of an explosion and fire in a multi-tenant industrial building at 901 N. Ridge Ave.

Upon arrival, firefighters said they discovered evidence of an explosion, damage to the south side of the building and fire in one of the tenant spaces.

Building owner Alex Munoz of Medinah said the damaged space was occupied by Star Tech, Inc., a welding supply company.

Munoz said the company's owner was locking the door at the end of the business day when the explosion occurred. Authorities said the man was slightly burned on the arm.

The fire, which took crews roughly 15 to 20 minutes to extinguish, damaged only one of the two units occupied by Star Tech, Munoz said.

"By the time I made it here, the fire was gone and most of the damage was contained to the front wall," he said.

Munoz said the building units were used primarily as storage space and would not have had any flammable materials inside. Most of the damage was structural, he said, and most of the unit's contents were unharmed.

Initial damage estimates were set between $75,000 and $100,000, authorities said.

Battalion Chief Mike Torrence, head of the fire department's investigation unit, said his team was working with the DuPage County Fire Investigations Task Force to determine the cause of the explosion.

Lombard building department workers were called to the scene Monday night to evaluate the structural integrity and safety of the building before the investigation began, Torrence said.

After a sagging roof caused an initial delay, crews stayed until about 5 a.m. Tuesday inspecting the unit.

Torrence said he expected the investigation to continue today.

"It's been a very slow process," Torrence said. "We're still waiting to speak with the insurance company on some issues."

Though it is still early, Torrence said investigators have not ruled out criminal activity as a cause.

"It's always a suspicion," he said. "Right now, it's a ruling-out process."