One person was found dead Wednesday in a Maple Grove commercial building that was heavily damaged by fire the night before.

The Maple Grove Fire Department said the cause of the fire was undetermined following a preliminary investigation by the Minnesota state fire marshal and Hennepin County.

Fire officials said they were called to the scene about 6 p.m. Tuesday. They were told that three people were inside the building at Hanson Implement and Storage, which is in the 18400 block of Bass Lake Road.

Two people were rescued and one of them was taken to the hospital, Fire Chief Tim Bush said. One person remained unaccounted for in the hours after the fire.

On Wednesday, Fox 9 reported that the owner of the business said his sister-in-law was found dead in the building and that her husband was in the hospital. The station said they lived near the building and helped take care of the property.

Bush told KSTP-TV that it was time-consuming for crews to sift through the debris.

"Because of the nature of the way this type of fire rolls out, it leaves piles of debris that have to be moved methodically at a time. Kind of like stripping back layers of an onion," he told the station. "It's time-consuming, and it takes a lot of effort."

The Fire Department said the medical examiner would release the victim's name once it is confirmed.

The building stores boats and RVs over the winter, according to fire officials. There were propane tanks inside the building, which caused several small explosions while crews were working to knock out the flames.

Fox 9 said the building was considered to be a total loss.