Jon Jones Arrest, 911 Caller Said Alleged Victim Had Bloody Nose, Mouth

A security guard claimed Jon Jones' fiancee was bleeding from the nose and mouth -- and was scared to return to the hotel room where the UFC champ was staying -- in a 911 call before his arrest.

"We've got a possible DV call. Domestic violence call. Female is bleeding from the nose and mouth," a Caesars Palace security official told Las Vegas Metro PD dispatch around 4:30 AM on September 24.

Security almost immediately informs dispatch the male suspected of being involved in the incident is "professional MMA fighter, Jonathan Jones."

FYI, Jones was in Vegas because his epic 2013 fight against Alexander Gustafsson was inducted into the Hall of Fame.

Despite the alleged injuries, security tells the 911 operator the woman has not accused Jones of getting physical with her ... but he's clearly suspicious.

The caller says the woman was asking for help, but didn't want to grab her stuff from the room, despite an escort from security.

"She's trying to get assistance, but she's refusing to go back up to the room."

Jon's fiancee -- who was with her 3 daughters -- received first aid ... but refused any further medical assistance.

Remember, Jones was ultimately arrested for misdemeanor domestic battery and tampering with a vehicle ... for allegedly smashing his head into a cop car while handcuffed. The damage is said to be north of $5,000, making it a felony.

It's unclear what started the alleged incident, but Jon's fiancee told police he returned to the hotel room from a night at the strip club, and was in a bad mood.

Days after his arrest, Jon broke his silence, saying he was swearing off alcohol from now on.