Public schools in LA have temporarily closed as a planned three-day strike by service workers employed by the Los Angeles Unified School District (LAUSD), the second-largest public school district in the US, began on Tuesday.

Last-minute efforts to prevent the strike, which centers on demands for better pay and additional staffing, failed. The Service Employees International Union Local 99, which represents around 30,000 cafeteria workers, bus drivers, custodians, and special education assistants, said its members had no choice but to strike. United Teachers Los Angeles, which represents around 35,000 teachers, joined the strike.

The union is seeking a 30% wage increase and says that the district has failed to negotiate a settlement. District officials dispute the union’s salary figures and have offered a total pay increase of over 20% over several years, as well as a 3% bonus.

LAUSD has around 430,000 K-12 students.