Revised statements provided by three swimmers contradict Ryan Lochte's initial claims of an armed robbery, the USOC said.
The United States Olympic Committee has apologised to the Brazilian people and condemned the actions of four members of the American swim team who apparently concocted a tale of armed robbery earlier this week.
A statement released late on Thursday by USOC CEO Scott Blackmun said swimmers Gunnar Bentz, Jack Conger and Jimmy Feigen gave statements to Brazilian police that contradicted initial claims by the fourth member of the group, Ryan Lochte, who said they had been held up by gunmen.
Law enforcement officials failed to find any corroborating evidence or witnesses and surveillance video released on Thursday appeared to show what actually happened. The swimmers stopped at a Rio gas station after a late night out and one of them vandalised a restroom, leading to a confrontation with armed security guards who demanded payment for the damage.
"The behaviour of these athletes is not acceptable, nor does it represent the values of Team USA or the conduct of the vast majority of its members," Blackmun's statement read in part.
"We will further review the matter, and any potential consequences for the athletes, when we return to the United States.
"On behalf of the United States Olympic Committee, we apologise to our hosts in Rio and the people of Brazil for this distracting ordeal in the midst of what should rightly be a celebration of excellence."
The statement said Bentz and Conger - who were prevented from leaving Brazil on Wednesday night - have now departed Rio and Feigen hopes to join them as soon as his passport is released by authorities. Lochte has already returned to the US.
USA Swimming executive director Chuck Wielgus also put out a statement on Thursday, saying the organization does "not condone the lapse in judgment and conduct that led us to this point. It is not representative of what is expected as Olympians, as Americans, as swimmers and as individuals."
The organisation will review the incident to determine what sort of discipline might be appropriate.