A fire in a two-family structure on Vesper Street in Portland produced heavy smoke and interior damage but no injuries.

The fire at 27 Vesper Street broke out shortly after 1 p.m. today, starting in the walls on the first floor and extending to the second floor, said Portland Fire Deputy Chief Steve Smith. Firefighters had contained the blaze within the hour.

Fire officials are still investigating the cause, but Smith said he does not believe the fire was suspicious.

No one was home when the fire occurred.