Thousands of Los Angeles Unified School District employees plan to announce a three-day strike at a rally on Wednesday, in a move Superintendent Alberto Carvalho told parents would likely force the nation’s second-largest school system to shut down for days without access to even remote classes.

About 30,000 workers who are members of SEIU Local 99, which represents bus drivers, custodians, cafeteria employees, campus security and teaching assistants, are asking for the district to “use the district’s $4.9 billion in reserves to invest in staff, students, and communities” to pay for a 30% raise and $2 per hour equity wage increase. The district’s 35,000 teachers. represented by United Teachers Los Angeles, are expected to join.

“Workers are fed-up with living on poverty wages – and having their jobs threatened for demanding equitable pay! Workers are fed-up with the short staffing at LAUSD – and being harassed for speaking up,” Local 99 Executive Director Max Arias said in a statement.

The school district has offered, in part, more than a 15% raise, retention bonuses and to bring its minimum wage up to $20, Carvalho wrote in a letter to parents on Monday evening. 

Schools will be open on Wednesday, said Shannon Haber, a spokesperson for the district, in an email to USA TODAY.

If the union and the district don’t come to an agreement and schools close, more than 600,000 students and their families would be affected by the “tremendous upheaval,” Carvalho said. The closures would hit when students are struggling to make up for time lost to the pandemic and end-of-year tests loom.