The high school I attended was said to be haunted by a girl who had been pushed off of the bell tower and broke her neck causing her to pass away. Before it was turned into a modern day high school, I believe it was an all girls boarding school which would have been around the time that this unfortunate event happened.
There were a few small stories circulating about the school being haunted, but alas they could have been rumours and completely made up, however, I had an experience of my own that made me believe them to be true.
I'll start with one of the stories I heard from others:
Either a teacher or a student, I forget which, needed a guide dog or a therapy dog which they would bring into the school with them, however, the dog would refuse to go anywhere near the stairwell which led to the bell tower. It would whine and wouldn't go towards the bottom end of the second floor ICT corridor, which is where the doors lead out to the stairwell (it's also where I had my own experience!)
I'd also like to add that there is no longer a bell in the bell tower, it wasn't there when I first started at the school and it still isn't there to this day, I believe it was removed and the door leading up to it was sealed shut meaning even if we ascended the stairs to it, we wouldn't be able to get much further than that said flight of stairs.
Now onto my own experience:
It was lunch time and I'd taken a shortcut through the maths corridors and into the ICT corridor on the second floor towards the door that leads to the stairwell, one set of stairs lead down to a small foyer and the canteen and the other set of stairs lead up, towards the bell tower. As I was walking along the ICT corridor I realized that it was awfully quiet, no one was around, no teachers or students whatsoever. Except, the set of footsteps walking behind me. I thought it must have been another student so I didn't bother turning around to look who it was. I got to the doors, which are big heavy wooden doors that don't stay open on their own. They need to be pushed with quite some force to a heavy duty magnet that holds them open until you press a button to release them. So I get to the doors and I push one of them open, not bothering to latch it to the magnet on the wall, thinking the person walking behind me will just catch it as I let go and walk through it too down to the canteen for lunch.
As I began walking down the set of stairs to the canteen I suddenly stopped mid-step. I realized the doors hadn't made the noise they do when they slam shut and the footsteps had stopped. I waited for someone to pass me on the stairs but nobody did so I turn around and... The door I walked through is stood open on its own, without being latched onto the magnet. It was ajar, far enough open that I could see down the corridor but not quite far enough for it to catch the magnet. And the student I thought was walking behind me is nowhere to be seen even though I could have sworn up and down they were right behind me as their footsteps weren't even that far away. Before I could even gasp, the door shuts... Slowly. As if someone was holding it open and then shut it slowly and gently so it wouldn't make a noise. I literally couldn't get out of there quick enough and I turned and ran down the rest of the steps. I never took that shortcut alone again and always made sure I went the long way around if no one was with me. What was even more weird to me was the fact that it felt as if someone were watching me and this whole event unfold. Creepy!
Lilpeachyclown; let me comment again, this clown is surely creepy!
I actually have reports on relationships of Bells and clowns. A bell tower is kind of like a church for clowns, there were reports saying that there was a famous "bell" in England, well you might have heard of it but I will remain silent for it, since we can't state a specific place just in case. Well that famous bell was known to be haunted by multiple clowns of some famous criminals, which include a queen of some era. Some sees a headless lady standing at the tower, some sees a man dragging the heavy chain up the stairs, rumors goes on.
Well, this actually can happen in any historical buildings, human beings tempt to "see things" when they feel unsure about something, like all the rumors of your school that you heard, the unsureness would illuminate some fear inside you and the stress of the fear that you feel may "make things up" and sometime can confuse a normal person.
No,no, not that I am saying that it is fake, the rumors might be true but as you said no one knows for sure. For all this rumors that you have heard, you might have felt some fear, a normal person will be confused by their own mind too while sensing fear. Just one possibility for the situation that you have written.
Now, backing up my first comment of the relationship of bell towers and clowns, like in anywhere that you religiously pray, there are always bells (I know that certain religions don't, let's say those with a bell in the building). When a person dies and returns to the world as a clown, it is said that they will remember the last thing that they hear (perhaps the loudest things that they hear?) that would be the bell, church bells (or any bells). That is why there are certain clowns which will appear in the bell tower; perhaps this would be another theory that could help you out? So far I could smell lots of possibilities in your clowns and I like it;)
Blessing from São Paulo