The Duluth Fire Department responded to a structure fire in the Lincoln Park neighborhood just before 1:00 a.m. Sunday.
Crews arrived at 320 N 21st Ave W. and found heavy fire in the attic of a two-story duplex. The duplex was quickly evacuated.
A second house starting on fire resulting in a second alarm being called.
The fire extended through the roof and collapsed the ceiling. Crews were forced to leave the building and continue fire attack from outside.
During a search, one dog was found and safely removed. One cat remains unaccounted for. No injuries were reported.
Fire crews remained on scene for just over three hours.
Initial damage estimates are $35,000 for the structure, and $15,000 for contents.