This morning after two of my family members showered in the upstairs bathroom there was a leak on the downstairs ceiling.

The bathroom upstairs is right about the kitchen that is downstairs and there is a watermarked path that is about 4 inches wide that runs about 5 feet long and ends with part of the ceiling that had ruptured because the water started to I suppose pile up at the end of this 5foot watermark and leak at this spot.

It seems to me that the leak runs the same way the bathtub upstairs is positioned (going west-east as the tub is west-east positioned).

We've previously had the tub leak before but it was from the tub knob/pipes and was fixed from the sharing wall with a room.

Is it possibly that there is some kind of leak with the tub itself or has some sort of pipe burst/leaked of is this completely hard to tell (which it probably is) from just the details I have given?

Our bathroom consists of 2 sinks a toilet and a bathtub with tiled walls and a glass door instead of curtains to keep water from splashing outside of the tub.

Any advice would be thankful.
We haven't tested to see if we can run the sinks or the toilet and see if the water leaks any or tested the tub. Is this something that should be done just to see where the leak might originate from? I don't want to cause any more damage with this cause-and-effect otherwise.

this morning after two of my family members showered in the upstairs bathroom there was a leak on the downstairs ceiling.
They showered in the tub, correct?
And it's also only when someone showers, also correct?
If that's the case I'd check the tile grout where the shower stream hits it. Tile grout will shrink over the years allowing to get past the tile and seep down the drywall onto the floor into your ceiling.
Check the grout for shrinkage and regrout if necessary. Good luck, tom