SAN FRANCISCO (KGO) -- A message displayed on screens of the Muni systems in San Francisco read 'you hacked' on Saturday as an outage caused all fare payment machines to shut down.On Sunday morning, Muni officials said fare gates and machines were operating again.Muni underground stations were experiencing outages since Friday afternoon, with the bulk of the delays and issues happening Saturday afternoon.SFMTA spokesman Paul Rose confirmed that the stations were hacked and that systems were compromised, causing many Muni riders to use the service for free.