Ezekiel Elliott was involved in an altercation Sunday night at Uptown Dallas' Clutch Bar, a source told SportsDay, the latest troubling off-field episode by the Cowboys' star running back who is already under investigation by the NFL.

Dallas police say a man was struck in the nose and taken to a nearby hospital for treatment. The incident is part of an ongoing investigation for aggravated assault. Elliott has not been named by the police as a suspect or as someone who was involved.

Exterior of the Clutch Bar, located at 2520 Cedar Springs Rd in Dallas, Texas, photographed Monday July 17, 2017. This is where the alleged incident with Dallas Cowboys Ezeikel Elliott happened on Sunday night.(Ron Baselice/The Dallas Morning News) (Ron Baselice / The Dallas Morning News)

But as details emerge, they could influence whether the NFL and commissioner Roger Goodell decide to discipline Elliott, the league's leading rusher last season and one of its brightest young stars. The NFL is aware of the matter and gathering facts, according to a league spokesman.

ESPN reported last week that Elliott was already in line for a one- or two-game suspension over claims of violence made last year by a female acquaintance.

Elliott denied wrongdoing and is not facing charges in those incidents, but he can be suspended by the NFL anyway. In the meantime, Elliott has continued to show questionable decision-making and behavior, even after saying he is aware of the need for caution because of his high-profile position.

The Cowboys depart Saturday, also Elliott's 22nd birthday, for training camp in Southern California.

Dallas police said they were sent about 9:40 p.m. Sunday to the 2500 block of Cedar Springs, where Clutch is located, to investigate a disturbance call. A 30-year-old man told police that someone he didn't know assaulted him. Police records show the blow caused "serious bodily injury."

Police records identify the alleged victim as Nkemakolam "Daryl" Ibeneme, who regularly is a DJ at Dallas-area clubs and also goes by "DTrain." He did not respond to requests for comment.

TMZ Sports released video from the scene that it says shows the alleged victim moments after being struck in the face, lying on the floor and holding his nose before being loaded into an ambulance.

At least one person on Twitter claimed to witness Elliott strike another person. He did not respond to requests for comment.

Elliott's representatives and the Cowboys also did not respond to questions about the matter.

Cowboys receiver Dez Bryant tweeted, in part, that Elliott "could have been defending himself."

The incident is part of a precipitous pattern for Elliott, whom the Cowboy selected with the No. 4 overall pick in the 2016 draft out of Ohio State and who exceeded even massive expectations on the field last season.

It's been away from football where he's struggled. Elliott came under scrutiny in March for pulling down a woman's top and exposing her breast at the St. Patrick's Day block party in Dallas' Lower Greenville neighborhood. The incident was caught on video.

He also visited a marijuana dispensary in Seattle, where pot is legal, before a preseason game there. He was at a bar in Columbus, Ohio, in February when one of his closest friends was arrested for trying to carry a firearm into the establishment.

ESPN reported that he and his representatives last week received the league's findings of its year-long investigation into Elliott's behavior and were expected to respond this week.

As the Cowboys wrapped up their offseason program in June, Elliott said he was wising up as he headed into a month's worth of free time.

"Just kind of want to stay out of the way," Elliott said. "Whatever you do is going to be seen."

When Elliott was asked about what he's learned from offseason issues, he said: "It's just life. You learn from your mistakes. If you don't, it can be brutal."

Elliott infused the Cowboys with his energy and talents last season, rushing for 1,631 yards and 15 touchdowns, and he has said he wants to take on an even bigger role this season as Dallas tries to win the NFC East again and move past playoff disappointments.

He and quarterback Dak Prescott often goof around in the locker room, and his memorable hop into a Salvation Army Red Kettle as part of a touchdown celebration last season showed off his fun-loving side.

He re-enacted the hop last weekend as part of the National Fantasy Football Convention held among fans in Fair Park.

But Elliott has also been known to struggle when fans approach him off the field, and he left the event's VIP party last Friday night in Dallas' Design District in frustration.

Elliott is not the only Cowboy to make headlines this offseason for the wrong reasons. Linebacker Damien Wilson was arrested July 4 on allegations he backed his pickup into a woman and flashed a rifle at her brother-in-law at Toyota Stadium, which was hosting an FC Dallas match and a fireworks show that night. Wilson is charged with two counts of aggravated assault with a deadly weapon. Wilson's attorney has since denied the allegations.

In late May, cornerback Nolan Carroll was arrested on suspicion of driving while intoxicated after officers reported that he was seen driving on the wrong side of the road.

Staff writer Jon Machota contributed to this story.