More than 30,000 Los Angeles teachers demanding higher pay and smaller class sizes have walked off the job in the second-largest US school system, union officials say, leaving 640,000 students in limbo.
Students arriving for classes at about 900 campuses in the Los Angeles County School District were met by teachers carrying picket signs and rallying in the rain for higher salaries, increased staff and smaller classes, the city's first teachers' strike in three decades.
The action is the latest in a wave of teachers' strikes across the US, following large-scale actions that began in West Virginia and spread to Kentucky, Oklahoma and Arizona.
While those cases represented unions battling Republican-dominated state legislatures that had focused on cutting spending, the Los Angeles strike is the largest targeting a Democratic-controlled government.
Los Angeles County officials contend the strikers' demands are unaffordable.
Videos posted on Twitter by the United Teachers Los Angeles, showed teachers and others marching with picket signs outside of a local public school chanting.
"The district would like us to believe that class sizes don't matter," said Mabel Wong, a teacher at John Marshall High School, during a news conference on Monday.
The union wants a 6.5 per cent pay raise, more librarians, counsellors and nurses on campuses, smaller class sizes and less testing, as well as a moratorium on new charter schools.
Talks broke down on Friday, when union negotiators said they were "insulted" by the latest offer of a 6 per cent salary increase from district officials.
Some teachers in Denver also walked out on Monday amid salary negotiations, according to a video posted on the Denver Classroom Teachers Association's Twitter page.
Los Angeles County School Superintendent Austin Beutner said Friday's offer to teachers was beefed up after newly installed California Governor Gavin Newsom increased education spending in his proposed budget for the coming fiscal year.
County officials have said UTLA's demands would bankrupt the district.
"Our commitment to our families is to make sure all of the money we have is being spent in schools. We are doing that," Beutner said in a statement on Friday.
"We hope UTLA leadership will reconsider its demands, which it knows Los Angeles Unified cannot meet."
Australian Associated Press