Chicago Bulls forwards Bobby Portis and Nikola Mirotic were involved in a "serious altercation" at practice Tuesday that sent Mirotic to the hospital.

According to The Vertical's Shams Charania, Mirotic, who recently returned to the Bulls on a two-year, $27 million deal, will be out indefinitely after a "shoving altercation during practice ended with an alleged cheap shot from Portis to Mirotic's face."

In a statement released Tuesday night, the Bulls confirmed Charania's report and announced Mirotic was diagnosed with maxillary fractures and a concussion. 

The Chicago Tribune's K.C. Johnson followed up and said Portis is likely to miss "a few weeks." 

CSN Chicago's Vincent Goodwill, USA Today's Jeff Zillgitt and ESPN's Adrian Wojnarowski relayed additional details: 

In 70 appearances a season ago, Mirotic averaged 10.6 points and 5.5 rebounds per game on 41.3 percent shooting from the field and 34.2 percent from three. 

On a rebuilding Bulls team, Mirotic was the favorite to open the season as the team's starting power forward.

Without his stretch-4 stylings, the Bulls will be left with Portis—who is now facing possible internal discipline, according to the Bulls—and rookie Lauri Markkanen as their primary options alongside center Robin Lopez.