Cops Don't Believe NFL Player Involved in L.A. House Party Shooting

There were no NFL players involved in the fatal shooting at a raging house party in a swanky Los Angeles mansion, contrary to reports ... at least according to cops.

Law enforcement sources tell TMZ ... they believe the Mulholland Drive mansion party that ended when shots rang out was a gang-related bash for the 8-Tray Gangster Crips, and they say they don't have any evidence to support an NFL player being there.

The fatal shootout went down early Tuesday morning, ending the wild party and sending three people to the hospital, one of whom is now dead. The other two gunshot victims are in critical condition.

While a man who claimed to be the head of security told CBS L.A. the party was in celebration of a player recently getting drafted by an NFL team, our law enforcement sources say cops believe the NFL player scenario was a cover story if any trouble happened. It's maybe not the brightest excuse -- the NFL Draft was held in April and rookies are already in training camps.

Video shows the moment gunshots ring out on the property, which was crawling with hundreds of people, many of whom were dropped off in buses. The driveway was also packed with luxury cars.

Our sources say the party had cake, balloons, decorations and loads of Crips ... but to their knowledge, no NFL players.