UPDATE: 2/5 at 2:58 pm

Charges are expected to be filed against two people accused of causing a fire at a Wausau home early Monday morning.

According the Wausau Police Department incident report, two people are being referred to the District Attorneys Office for negligent use of burning materials.

The Wausau Police Department tells NewsChannel 7 the investigation is ongoing.

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ORIGINAL STORY: 2/4 at 7:07 am

Investigators are trying to figure out what caused an apartment building to start on fire Monday morning.

Crews were called to the building on the 100 block of South 4th Avenue on Wausau's west side around 6:15 a.m. Battalion Chief Paul Czarapata with the Wausau Fire Department says, "We arrived and found smoke coming from the front of the house and fire on the 2nd floor in the rear of the house. I did a walk-around but there was also some fire on the first floor in one of the walls."

There were four people inside the building at the time of the fire, they all made it out safely. However, he says a child had to be transported to the hospital for possible smoke inhalation. The fire was bad enough, that the occupants will have to be relocated. Czarapata says the building had three units inside, only two of them were occupied at the time.