Things got so intense between referees at a youth basketball game in Colorado that they ended up throwing punches in front of a bunch of kids ... and now police tell TMZ Sports they're investigating the melee.
The ugly scene, which was captured on video, went down during a 4th-grade boys hoops game -- Cherry Creek vs. Legend Blue -- over the weekend at the Gold Crown Field House in Lakewood, CO.
The clip clearly shows two referees square up on the court after some type of disagreement ... when one of the refs throws a massive right hook, knockin' down the other official.
The ref attempted to throw more punches, but was held back by bystanders.
The ref who was dropped eventually got up ... but he wasn't done fighting. The man then got into a stand-off with another official ... but thankfully no punches were thrown this time.
We talked to Lakewood Police ... who told us they're aware of the situation, but haven't yet made any arrests because "the involved parties had already left the gym" by the time they arrived on scene.
Thankfully, no one was injured during the fight, according to the Gold Crown Foundation ... which also tells us all the referees have been suspended indefinitely.
"We have informed these independently contracted officials that they are suspended indefinitely from working for Gold Crown Foundation," GCF told us in a statement.
"Most importantly we apologize to everyone that had to witness their unacceptable behavior - especially the kids."
They continued ... "We look forward to getting our league back on track, and resume what will be a great season for the kids."