In the audio recording, the man believed to be Sterling questions his girlfriend, V. Stiviano, about her association with minorities. TMZ reports that Stiviano, who is black and Mexican, posted a picture of herself with Magic Johnson on Instagram, a photo that has since been removed.
"It bothers me a lot that you want to broadcast that you're associating with black people. Do you have to?" the man believed to be Sterling says. He continues, "You can sleep with [black people]. You can bring them in, you can do whatever you want. The little I ask you is not to promote it on that ... and not to bring them to my games."
In addition to the NBA investigation, the Clippers have opened their own investigation, team president Andy Roeser said in a statement.
"We have heard the tape on TMZ. We do not know if it is legitimate or it has been altered," he said. "We do know that the woman on the tape -- who we believe released it to TMZ -- is the defendant in a lawsuit brought by the Sterling family alleging that she embezzled more than $1.8 million, who told Mr. Sterling that she would 'get even.'
"Mr. Sterling is emphatic that what is reflected on that recording is not consistent with, nor does it reflect his views, beliefs or feelings. It is the antithesis of who he is, what he believes and how he has lived his life. He feels terrible that such sentiments are being attributed to him and apologizes to anyone who might have been hurt by them."
Rochelle Sterling, Donald Sterling's wife of more than 50 years, filed a lawsuit against Stiviano, asking for the return of all cash, land, cars and other gifts Donald gave Stiviano that under California law are the community property of the Sterlings. The gifts include a duplex worth $1.8 million, a Ferrari, a Range Rover and two Bentleys. The lawsuit states Stiviano knew the gifts given to her were provided without the "knowledge, consent or authorization" of Rochelle Sterling.
The lawsuit also states Donald Sterling had asked Stiviano to return the gifts and she refused.
An ABC News reporter on Saturday attempted to contact Stiviano at her home, but she refused to answer the door. She had posted signs saying she had no comment and to contact her lawyer.
Players around the league began reacting as news of the investigation spread.
Clippers star Paul issued a statement.
"On behalf of the National Basketball Players Association, this is a very serious issue which we will address aggressively," it read. "We have asked [Sacramento] Mayor Kevin Johnson to expand his responsibilities with the NBPA, to determine our response and our next steps. As players, we owe it to our teams and our fans to keep our focus on our game, the playoffs, and a drive to the Finals."
Johnson, for his part, called the comments "reprehensible and unacceptable." He is a former NBA All-Star guard and chairman of a search committee to find a new director for the union.
"It's a damn shame but a sad reality that we have people in the world who continue to further such ignorance," Lakers star Kobe Bryant told ESPN's Stephen A. Smith. "I would not want to play for him."
Warriors coach Mark Jackson, whose team is playing the Clippers in a first-round playoff series, said he was "disappointed in the comments made."
It's "unfortunate," he continued. "I believe there's no place in society for those feelings, and it's just sad."