12/9 2:34 PM PT -- 12/9 -- TMZ Sports has obtained Burfict's mug shot ... and yeah, it ain't hard to tell the dude was PISSED about getting arrested.
We've also obtained police documents from the case ... and in them, a security guard says Burfict and two other men were the aggressors at around midnight on Dec. 4.
The guard claims he was helping another security guard calm down Burfict and his pals when one of the men "was recording on his phone and placed it in my face and stated 'what the f*ck these dudes doing behind us look at these clowns following us.'"
The guard alleges in the docs that things got physical with him and the other guard while they were on a Cosmo escalator together.
In the docs, the guard alleges one of the men tried to shove him down the escalator. The guard also claims another one of the men took a swing at the other guard.
It's not clear in the docs which man was allegedly Burfict.
Burfict is due in court on Feb. 3 for a hearing in the case.
NFL linebacker Vontaze Burfict was arrested for allegedly attacking a security guard at a Vegas casino over the weekend, TMZ Sports has learned.
The 30-year-old former Cincinnati Bengals star -- who later played for the Raiders -- was taken into custody for misdemeanor battery ... but nobody knew why, until now.
A spokesperson for the Las Vegas Metro Police Dept. tells us ... Burfict was arrested Saturday for battering a security officer at The Cosmopolitan resort, casino and hotel.
But, the backstory is wild ...
Multiple sources tell us Burfict and at least 1 other person were looking for a restaurant at the Cosmo called "Secret Pizza." ... which is intentionally hard to find!
It's like a speakeasy for pizza -- a hidden eatery located at an unmarked location on the Cosmo property. We know what you're thinking ... how's the food? It's got 4 stars on Yelp!
Though Barstool's Dave Portnoy once did a Pizza Review from there -- he wasn't as impressed.
We're told Burfict and his crew were having a tough time locating the place -- and at some point, they felt like security was following them.
At one point, there was an incident between Vontaze and the security guards -- with the guards claiming Burfict got physical.
Security detained Burfict until police arrived -- that's when he was formally arrested.
We reached out to Burfict's camp to get his side of the story -- we'll let you know when we hear back.
Originally published -- 12/7 9:44 AM PT