The fire happened around 2:30 p.m. Thursday in the 1400 block of 99th Street.
Crews found two children — a seven-year-old girl and an 11-year-old boy — and their 39-year-old mother inside the home, RCMP said.
Their names have not been released, but police said family members have been notified.
Police said the investigation includes whether or not the deaths are suspicious.
Autopsies are scheduled for a later date, police said.
Saskatchewan RCMP said highly trained investigators, including members of the major crime unit, have been deployed to North Battleford to assist local officers with the investigation.
Battlefords RCMP is asking anyone who has information to contact them at 306-446-1720 or Crime Stoppers at 1-800-222- 8477.