Duluth, MN – “It was quite an explosion,” assistant fire chief Jim Ray said. “One half of the duplex was completely destroyed and leveled. The other half was severely damaged – all the walls are bowed out and the windows are blown out.” In addition, the floors are unstable, he said.

Building debris – lumber, doors, glass and siding – was scattered in all directions up to 200 feet away. A neighbor’s car, parked about 75 feet away, had its rear window broken and was hit by the duplex’s garage door and living room window frame.

“A hundred feet away I’m finding doors and there are pieces of siding up in trees,” Ray said. “You can tell it was a very large explosion.”

The blast woke neighbors, who said the explosion lit up the area like it was daytime. A neighbor declined to be inter-viewed this morning, saying police and fire officials asked him not to talk to anyone.

“They looked out the window and saw a huge orange fireball the size of the building,” Ray said.

When firefighters arrived, they found a number of small fires scattered throughout the rubble.

The blast also damaged some nearby structures. The explosion shifted one neighbor’s garage sideways; the door on an-other garage was deformed. Objects were knocked off of walls in nearby buildings.

“Fortunately, the side of the building that exploded was facing away from neighboring homes as much as possible,” Ray said. “If the other side had exploded, it would have been much worse.”

Just before 8 a.m. smoke began coming from the attic near where the standing unit and the destroyed unit had joined. Flames became visible within minutes. The unstable condition of the building prevented firefighters from fighting the blaze from inside, and the structure’s damaged condition allowed the fire to rapidly spread. The roof collapsed around 8:30 a.m.

Low water pressure also prevented firefighters from pouring much water onto the blaze for about 30 minutes.

At the scene, assistant fire chief Richard Mattson said low water pressure complicated the department’s efforts. He said crews would protect nearby structures, but wouldn’t save the building because it was structurally unsafe.

“We’re not going to put it out,” he said. “We’re going to keep it away from neighboring buildings.”

The front second-story wall collapsed around 9 a.m., and the back of the second story collapsed later. Fire crews remained on the scene until noon.

Fire investigators were on the scene before the flames reappeared, but did not have time to determine a cause of the blast. Ray suspects a natural gas leak is to blame.

Investigators will return to the scene Tuesday morning in an effort to confirm that and try to determine what might have ignited the blast.

The building is owned by Timothy Collelo of Cloquet, according to city records. The property and structure had an esti-mated market value of $564,000, according to the city assessor’s office. Collelo could not be reached for comment.