Duluth Fire Department crews responded to a blaze Tuesday morning at 216 E. Fifth St. in the Central Hillside neighborhood.
The fire began about 4:05 a.m. in the unoccupied, condemned building. The same building suffered a structure fire in April, Assistant Chief Erik Simonson said.
An occupied house on the west side of the fire sustained significant heat damage, but firefighters were able to prevent the fire from spreading to the home's interior.
The cause of the fire is under investigation.
