NJ Transit’s entire rail system was subject to hour delays as of Sunday afternoon, due to “fire department activity” at the agency’s Rail Operations Center.

Alerts posted to the NJ Transit website and social media accounts around 12:30 p.m. Sunday said every rail line in the system was suspended in both directions.

A follow-up alert posted around 1 p.m. indicated that trains were moving again on all lines, but were subject to delays up to an hour.

The Rail Operations Center in Kearny is the hub of NJ Transit’s train network and it is where staff monitor and direct every rail line in New Jersey. It’s unclear exactly what happened at the facility.

It is unclear if Amtrak trains were also impacted Sunday. Amtrak did not immediately respond to a request for comment.

Sunday’s delays come after a fire damaged rail infrastructure outside the Hudson River tunnels and disrupted trains on Friday.

This story has been updated.