Wildfires in northwest Nebraska forced Chadron State College and a local school district to cancel classes Thursday as officials ordered evacuations along parts of U.S. 385 south of town.

About 150 residents from the Chadron area were at least temporarily moved from their homes, and the schools said classes would not be held for the rest of the week.

The two fires in Dawes County were started by lightning from a Tuesday thunderstorm. State, federal and local officials still were fighting the fires Thursday, one south of Chadron and the other between the smaller towns of Harrison and Crawford. State officials also were responding to fires in Sheridan and Sioux counties, all in the Nebraska Panhandle.

Authorities said a 64-year-old woman died of an apparent heart attack after her home was evacuated Wednesday night. Emergency crews took Ronni Davis to the hospital after a neighbor reported she was having breathing problems.

Gov. Dave Heineman on Thursday dispatched the state's mobile operations center to the region, and Lt. Gov. Rick Sheehy, the state's emergency management director, is expected to visit the area Friday.

The fires in Dawes and Sioux counties had burned 25,000 acres — almost 40 square miles — combined by Thursday afternoon. Two dozen displaced horses, a pony and a goat were being held at the Dawes County Fairgrounds.

Chadron residents said Thursday they could see massive smoke plumes to the south, but school and city officials said they do not think the blaze poses an immediate threat to the town.

"We're kind of lucky right now that the breeze is coming from the north," said Chadron High School athletics director Andy Pope, who answered the school phone Thursday. "That's keeping it from spreading into town. But who knows what will happen?"

Chadron State College spokesman Justin Haag said the campus will remain open, and administrators see no immediate danger. The cancellations will allow students to leave early for the Labor Day weekend, he said. Students living in residence halls were being allowed to stay, and he said those who leave early have been asked to check out at the front desk so staff can monitor who still is on campus.

Chadron State Park closed as well, and the Nebraska Game and Parks Commission was contacting those who had reserved a cabin for the Labor Day weekend.

Chadron Public Works Director Milo Rust said the fire intensified overnight, and local and state officials joined forces to fight it.

"The fire, at this moment, is not threatening the city," he told The Associated Press. "But we're making sure we're paying attention to what's happening and where it's going."

Associated Press newsperson Melanie Welte contributed from Des Moines.