NILES — Authorities are investigating what is believed to be an accidental house explosion Sunday at the 600 block of Vine St. in Niles. It’s unclear at this time whether the explosion caused a subsequent fire or whether a fire resulted in the explosion.

Police were dispatched to the location at 11:40 a.m. where they found a home fully engulfed in flames.

Niles Fire Department Chief Larry Lamb said officials were still investigating, but that they believe an explosion occurred.

“We do know we had some sort of an explosion,” Lamb said. “I don’t know at this point whether it is the result of a fire or what caused the fire. They [authorities] are [inside the house] doing the work.”

Initially, it was believed that someone was inside the home, but Lamb said authorities determined that there no one was in the house at the time of the fire. There were no injuries reported.

Lamb said the fire took about 20 minutes to get under control as firefighters used “blitz attack” method. It took a full hour to get the fire completely out.

“The big challenge, obviously, is you got a ball of fire — it is a rather small building and we are worried about exposures and we wanted to keep it off of the [neighboring house],” Lamb said.

Because of the force of the explosion, the west side wall had been pushed to the west, causing some structural concerns.

“Once I have got that concern, the last thing I want to do is give a firefighter’s life for a building we are going to tear down anyway,” Lamb said.

The house was considered a total loss. While the structure remained standing, the home appeared charred from the inside out, with remaining beams appearing black and burned. The west side wall of the home leaned to one side. Lt. Detective Rick Krueger with the Niles Police Department said the leaning wall indicates that this was likely an explosion.

“That usually does not happen during a fire, so we think there was [a force] of pressure,” Krueger said.

Residents of the home told authorities that they had been heat treating the house for an insect infestation. Lamb said authorities suspect that this treatment may have caused the incident, though an investigation is ongoing.

Krueger said officials found evidence to support this theory. Kruger said they believe that the residents were heat treating the home with space heaters and a salamander heater. He said the investigation so far had ruled out any problems with gas lines that could have caused the event.

“It’s very, very unlikely that that was the issue,” Krueger said.

Eight-year-old Heavyn Hein, who lives across the street, was in the backyard when she said she heard a loud boom. Hein said her dad, Mark Vowels, called the police for help.

“We heard the windows flash out immediately, like five minutes later the whole house caught fire,” Hein said.

Hein said she was extremely concerned because she knows the family across the street and was afraid that they were inside.

“I was freaking out and crying,” Hein said.

Lamb said it was fortunate that no one was in the home at the time of the incident.

“The beauty in all this is that nobody got hurt,” Lamb said. “Houses and stuff can be replaced, but people can’t.”

Niles city and Niles Township firefighters responded to the scene. SMCAS and the Berrien County Sheriff’s Department were also on scene. Representatives from the utilities department arrived to shut off power near the area.