Update: 11:13 p.m.
Containment has grown to 50 percent, as 250 personnel were in the area when the fire grew out of a nearby training burn Thursday afternoon, according to CalFire.
Crews are using low water fire suppression tactics as part of a critical fire fighting skills training class.
The Cook Fire incident report states: "CAL FIRE was conducting a critical training class for fire fighters in the use of low water fire suppression operations at the U.C. Berkeley Field Station, Yuba County. This training included the use of live fire for crews to train on fire fighting tactics. The original prescribed burn area was set at 212 acres in size. The fire is currently holding at approximately 180 acres within the burn area.
"CAL FIRE personnel aggressively engaged the spot fires within the burn area using engines, dozers, hand crews and aircraft. The fire is currently holding at approximately 180 acres, all within the prescribed burn area. Drought conditions will continue to influence fire behavior throughout the summer causing rapid aggressive fire activity. CAL FIRE reminds everyone to do their part and maintain a defensible space."
Update: 6:40 p.m.
The Red Cross has opened an evacuation center in Oregon House, California, to provide services to evacuees, according to the Red Cross NE Cal Twitter feed.
YubaNet reports the fire is at 180 acres and 25 percent contained.
Original story: 5:42 p.m.
A 100-acre fire is burning in Yuba County near Collins Lake.
Lynn Tolmachoff with Cal Fire says the cause of the Cook fire is undetermined, but it started near a firefighter training exercise at about one this afternoon.
"It's burning in what's called Oak Woodlands. We have a lot of oak trees dotted with scrub oaks and light, flashy fuels, dead, dry grasses, so, items that are ready to burn even though we're in the month of June. This drought has taken its toll obviously on everything."
Tolmachoff says fire departments from the county and neighboring counties are fighting the fire on the ground and from the air. She says firefighters hope to stop the fire's forward progress by this evening.