CHAMPAIGN – Almost 800 building-service and food workers walked away from their jobs and onto the picket lines at the University of Illinois’s Urbana-Champaign campus Monday, unhappy over wages and other issues in a contract proposal from the school.

It wasn’t immediately clear how the strike was affecting campus, but an email sent to university staff warned that delays and disruptions were expected in campus mail pickup and at least some building services. The university said other employees were helping cover the duties.

The 775 members of the Service Employees International Union Local 73 said they plan to strike for three days, after rejecting the most recent contract offer from the university Sunday. The four-year contract included a 50-cent-an-hour raise in the first year with smaller raises in later years, said John Hill, a janitor who’s worked for the university for 11 years and said he makes just more than $17 an hour.