AUGUSTA (AP) — Officials have been unable to pinpoint what caused an apartment building fire last month in Augusta that left 27 people homeless.

Sgt. Kenneth Grimes of the state fire marshal’s office told the Kennebec Journal on Friday that the Dec. 5 fire has been classified as undetermined.

Grimes said the massive fire and damage it caused to the 18-unit building left little evidence behind.

The 23 people who were home at the time escaped with a few suffering minor injuries. Investigators have said the building had working smoke detectors and two exits in each apartment which allowed the tenants to escape.