EDMONTON - Three people have been flown to Edmonton hospital after a fire at a Syncrude plant in Fort McMurray.

The blaze broke out in the 7-3 diluent recovery unit at Syncrude's Mildred Lake facility about 2 p.m. Thursday, said Cheryl Robb, Syncrude spokeswoman.

The plant handles napatha, according to the Syncrude website, which is an explosive solvant.

Emergency responders from the company extinguished the fire.

One Syncrude employee and four contractors were injured in the blaze. Two were treated and released from a local hospital.

The fire has not affected Syncrude operations, said Robb.

Families of the injured workers have been contacted.

An investigator from Workplace Health and Safety is on scene.