BEND, Ore. -

While crews keep watch for and douse more lightning-sparked holdover fires in Central Oregon, investigators have found the specific cause of three human-caused fires -- two discarded cigarettes and an abandoned campfire.

Incident 257 was reported around 1:15 p.m. Wednesday near Pringle Butte, about nine miles southwest of Sunriver. It was declared contained at about six-tenths of an acre about seven hours later. Investigators found that fire was caused by a discarded cigarette, said Deschutes National Forest spokeswoman Kassidy Kern.

An abandoned campfire was determined to be the cause of a small, 1/10 of an acre fire Thursday at Walton Lake on the Ochoco national Forest that was quickly contained and controlled, Kern said.

Also, Bend police said another cigarette-caused fire on the river trail by Mt Bachelor Village was put out by a passerby Thursday morning. It burned about three square feet, she said, and was fully contained by the time officers arrived.

Another small 1/10th-acre fire Thursday at Surveyor's Ice Cave, on the southern flank of Newberry Caldera south of Bend, was a holdover or "sleeper" lightning-sparked fire from thunderstorms earlier in the week, she said.

Meanwhile, the cause is still under investigation of Wednesday's second fire, reported around 5:30 p.m. on the Crooked River National Grassland near milepost 106 on Highway 97, in the area of the intersection with Highway 361 (the Culver Highway).

Smoke prompted some intermittent closures of the road to Culver, but it was reopened around 7 p.m. It grew to about nine acres by late Wednesday and remained 90 percent contained Thursday, Kern said.