A stampede erupted at the Barclays Center in Brooklyn after rumors began to swirl there was an active shooter in the arena.
At least 10 people suffered injuries just after midnight Sunday ... when people began screaming someone was firing shots. It wasn't true, but the crowd didn't know it.
It's unclear how the rumor first started, but it spread like wildfire. A security guard said the rumor was that someone was firing shots outside the arena. That caused people who were leaving the boxing match to make a mad dash back inside, and it became a madhouse.
Naomi Osaka was among those present ... she tweeted, that she heard "shouting and saw people running" and was then told "there was an active shooter and we had to huddle in a room and close the doors," adding, she was "petrified."
One person who was there tweeted, "I watched a person get trampled nearly out cold."
The ten known to be injured were taken to a hospital and according to officials, they suffered only minor injuries.
Obviously, the massacre in Uvalde, Texas was on everyone's mind, especially since authorities have said they are now worried about copycats.