Updated 4:32 p.m.
Two more airport police officers involved in dragging a passenger off a United Express flight at Chicago's O'Hare International Airport have been placed on leave.
The Wednesday announcement from the city's Aviation Department comes two days after another officer involved in the Sunday night confrontation was put on leave. The department said it is continuing its investigation.
Earlier Wednesday, the chief executive of United Airlines said the carrier will no longer ask police to remove passengers from full flights after the uproar over a man who was dragged off a plane by airport officers in Chicago.
In an interview with ABC's "Good Morning America," Oscar Munoz said he felt "ashamed" watching video of the man being forced off the jet. He has promised to review the airline's passenger-removal policy.
Munoz, who leads United's parent company, apologized again to Dr. David Dao, a Kentucky physician, his family and the other passengers who witnessed him being taken off the flight.
"That is not who our family at United is," he said. "This will never happen again on a United flight. That's my promise."
In the future, law enforcement will not be involved in removing a "booked, paid, seated passenger," Munoz said. "We can't do that."
Also Wednesday, a Chicago alderman said representatives from United and the city's Aviation Department have been summoned before a city council committee to answer questions about the confrontation at O'Hare Airport.
Ald. Mike Zalewski (23rd Ward) said he does not know who will represent the airline before the Aviation Committee, but Munoz has been notified of the hearing scheduled for Thursday.
Chicago Aviation Commissioner Ginger Evans will also speak.
Munoz called the embarrassment a "system failure," explaining that United will review its procedures for seeking volunteers to give up their seats when a flight is full. United was trying to find seats for four employees, meaning four passengers had to deplane.
It was at least Munoz's fourth statement about the confrontation.
After the video first emerged, he said the airline was reaching out to the man to "resolve this situation."
Hours later on Monday, his tone turned defensive. He described the man as "disruptive and belligerent."
By Tuesday afternoon, almost two days after the Sunday evening events in Chicago, Munoz issued another apology.
"No one should ever be mistreated this way," Munoz said.
The passenger was identified as Dao, a 69-year-old physician from Elizabethtown, Kentucky.
An attorney who represents Dao said his client was being treated at a Chicago hospital for injuries he sustained on the plane and that the family would not comment.
Dao's relatives are focused only on his medical care, attorney Stephen L. Golan said. The family "wants the world to know that they are very appreciative of the outpouring of prayers, concern and support they have received."
Airport officials have said little about Sunday's events and nothing about Dao's behavior before he was pulled from the jet that was bound for Louisville, Kentucky. Likewise, the Chicago Aviation Department has said only that one of its employees who removed Dao did not follow proper procedures and has been placed on leave.
No passengers on the plane have mentioned that Dao did anything but refuse to leave the plane when he was ordered to do so.
The event stemmed from a common air travel issue — a full flight.
At first, the airline asked for volunteers, offering $400 and then when that did not work, $800 per passenger to relinquish a seat. When no one voluntarily came forward, United selected four passengers at random.
Three people got off the flight, but the fourth said he was a doctor and needed to get home to treat patients on Monday. He refused to leave.
That's when three Aviation Department police officers boarded the plane. When Dao refused to leave his seat, one of the officers could be seen grabbing the screaming man from his window seat, across the armrest and dragging him down the aisle by his arms.
Other passengers on Flight 3411 are heard saying, "Please, my God," ''What are you doing?" ''This is wrong," ''Look at what you did to him" and "Busted his lip."
The U.S. Department of Transportation announced Tuesday that it is reviewing Sunday's events to see if United violated rules on overselling flights.