More than 13,000 students were out of school Thursday — and likely will remain so through Monday — after teachers in southern Oregon's largest district went on strike.

The walkout Thursday in the Medford School District occurred after all-night bargaining yielded no results. No new talks are scheduled until Saturday, and the district has canceled classes through Monday. If no deal is reached, the district plans to reopen schools Tuesday with substitute teachers and shorter hours.

The strike is the first in district history and only the fifth teachers' strike in Oregon in the 21st century. On Wednesday, teachers in the state's largest district, Portland, voted to authorize a strike that could occur Feb. 20.

Medford schools Superintendent Phil Long did not immediately return a phone call Thursday. In a statement to parents and the community, he said it was a "sad day" for him and he understands their frustration.

"This was a moment we've worked diligently to avoid over many months of negotiations, and particularly over the last two days," his statement said. "Our negotiating team did not sleep last night as we wrestled with numbers and various scenarios that we hoped would meet our students' long-term needs and still satisfy teachers."

KDRV-TV showed teachers picketing in the dark Thursday morning in front of school district offices.

Medford Education Association president Cheryl Lashley said salary, working conditions and retirement benefits remain sticking points.

"The only way for you to settle this now is for you — the community — to barrage the (school) board and get them to stop the playground antics and get this settled," Lashley said in a statement.

She told KDRV that the union made its last proposal at 2:30 a.m. and the board rejected the offer three hours later.

The Medford district has more than 13,000 students, making it the eighth-largest of the state's nearly 200 districts.