OGALLALA, Neb. (AP) — Firefighters have Western Nebraska wildfires nearly contained, but will be watching the skies for lightning that could spark more fires on the tinder-dry terrain.

Officials believe lightning started the five Keith County fires near Lake McConaughy at Ogallala on Thursday.

Three of the fires burned out of control Friday, but Nebraska Emergency Management Agency spokeswoman Jodie Fawl says at least one of the fires had been completely extinguished by Saturday, and two others were 100 percent contained.

A fire north of Brule is 75 percent to 80 percent contained, and another in northeastern Keith and southwest McPherson counties is 90 percent contained.

The wildfires have blackened more than 78 square miles. One firefighter suffered heat exhaustion Friday, but no other injuries or structure fires have been reported.