Detroit Pistons power forward Isaiah Stewart punched Phoenix Suns power forward Drew Eubanks in the face in a Footprint Center parking lot before the Suns’ 116-100 win over the Pistons on Wednesday, league sources briefed on the matter confirmed to The Athletic.

The Phoenix Police Department announced that Stewart was arrested for assault and issued a citation before being released. It’s unclear what sparked the altercation in Phoenix.

“Around 4:45 p.m. Phoenix police officers were working in a security capacity during a Suns home game at Footprint Arena when they were called to a fight between two players inside the arena’s parking lot,” Phoenix Police Sergeant Phil Krynsky said in a statement. “When the officers arrived, they were directed by security to the players involved. The players were identified as 27-year-old Drew Eubanks and 22-year-old Isaiah Stewart. Officers spoke to both players involved and a number of people who witnessed the incident. They learned there was an argument between both players as they arrived at the arena. Witnesses said the argument escalated when they saw Stewart punch Eubanks, causing a minor injury. Both men were separated by security which ended the fight. Detectives responded to investigate the incident and collect evidence. Stewart was arrested for assault, issued a citation and released. The investigation remains active.”

The NBA is expected to receive footage. The league is reviewing the matter, a league source said.

“We are aware of the incident between Isaiah Stewart and Drew Eubanks prior to this evening’s game,” Detroit said in a statement before the arrest. “We are in the process of gathering information about what happened and what provoked it, and responding to the NBA and local authorities.”

“The attack on Drew Eubanks was unprovoked, and acts of violence such as this are unacceptable,” a Suns spokesperson said. “We unequivocally support Drew, and will continue to work with local law enforcement and the NBA.”

During a Nov. 5 matchup between the two teams in Detroit, both Stewart and Eubanks were extra aggressive with each other and verbally sparring throughout the game.

“I know there were statements put out,” Pistons coach Monty Williams said of the altercation postgame. “I want to get all of the information.”

Williams said he talked to Stewart, and Stewart shared what happened. Williams continued by saying he thought the Suns saying the altercation was “unprovoked” was irresponsible. He believes more information should be gathered before saying something like that.

Stewart has missed the last several games with an ankle injury. He joined the Pistons on their West Coast swing to prepare for a return after the All-Star break. Eubanks was warming up following the altercation and two hours before the game.

Eubanks finished the game with six points, eight rebounds, two steals and two blocks in 18 minutes of action.