A one-day strike by workers at 13 German airports, including the Frankfurt and Munich hubs and all the country’s other main destinations, has caused the cancelation of most flights.

Air traffic at Germany’s major airports ground to a near standstill on Monday after labor union Ver.di called on ground personnel, baggage handlers and security staff to go on strike.

The 24-hour walkout, which started at midnight on Sunday, involves public-sector employees at the airports as well as ground and security staff.