The One Chicago universe has taken over as one of the most popular television franchises currently on the air.

“Chicago PD” dominated their 10/9c spot with 6.54 million.

Here is the real reason why filming has been halted for the franchise’s most popular series.

Cast of “Chicago Fire” posing

Just this week, we learned that another popular show had to stop its filming process.

“NCIS” was put on hold as a cast member tested positive for the virus (perDeadline).

Now, looks like “Chicago Fire” is dealing with the same issue.

Cast of Chicago Fire smiling

At the time, filming had just resumed after the holiday break.

There is no resume date known yet.