Nelson Fire and Rescue Services extinguished a fire inside the construction site in the 600 block of Vernon Street at 7:50 a.m. on March 12.
A news release from the Nelson Police Department states that firefighters allegedly found two Nelson residents inside the building with a burning campfire, which caused damage to the structure.
The pair were arrested and released on an undertaking to appear in court on June 4.
The investigation is ongoing and police will be recommending charges of mischief under $5,000.
The location of the fire is where a six-storey, 125-unit housing development for seniors is being built.