The forest fire had engulfed an estimated 35 square kilometres of land near Norman Lake by Monday night, spreading about eight square kilometres in a matter of hours.
Dozens of people have been forced to evacuate their homes in the area, about 50 kilometres southwest of Prince George, since the blaze was first reported on Saturday.
The B.C. government's Wildfire Management Branch says it expects the fire to keep growing because of dry and hot conditions, although it appears to have been caused by humans.
It says over 100 support staff are to arrive at the site to help crews that have been battling the blaze by both ground and air.
The branch says it is the province's first major expanded-attack fire of the season and has arrived earlier than usual.