Chris Pearson’s death was the result of someone losing it on him for being loud and disruptive in his apartment complex in the middle of the night … sources with direct knowledge.

Our sources say the former “Ex on the Beach” star was down in the pool area with his girlfriend, making a lot of noise around 2 AM Sunday. We’re told Chris was yelling … it’s unclear at who, but it pissed off the other residents who were trying to sleep.

We’re told Chris ignored everyone, but then someone on one of the balconies amped things up and was yelling hard at Chris, who in turn started screaming back at the guy. Our sources say Chris went inside the building to confront the guy … and that’s when he was fatally stabbed in the area around his heart.

Our sources say the guy who stabbed him fled before authorities arrived.

As we first told you … Chris was rushed to a hospital, but died around 3:30 AM from his injuries.

According to our sources … Chris was not normally a confrontational guy, but that wasn’t the case during the incident.

Law enforcement sources tell us … cops are investigating and looking for witnesses and videos that may help them figure out what went down, but so far no arrests have been made. Our law enforcement sources say cops are confident they’ll catch the guy.