Emergency services outside the mine on Tuesday morning. Photo: TT
Boliden, the company that runs the mine issued a statement in English saying that a fire had started in a plastic container 826 metes underground.
"The fire has now been extinguished and all employees have been evacuated," the statement added.
There were no reports of injuries.
Chief Fire Officer Mats Jansson told Swedish news network SVT at around 10am: "There is still burning and a lot of smoke".
Some of the trapped workers were understood to have been waiting in a "rescue chamber" inside the mine, before being helped out by emergency services.
Rescue chambers are safe spaces with fresh air, where staff can hide if a mine gets filled with smoke.
Boliden is a mining and smelting company, primarily focusing on copper, zinc, lead, gold and silver. With around 4,500 employees, the company was named after the Boliden mine near Skellefteå in northern Sweden after a gold discovery in the early twenties. It now has its head office in Toronto, Canada.