United Airlines has decided to refund the tickets for all the passengers on the flight from which a man was dragged out because it was overbooked, The Guardian reported on Thursday. They had put one officer on leave earlier, and have now done the same for the other three officers involved in the incident. The flight on Sunday was from Chicago’s O’Hare International Airport to Louiseville in Kentucky.

The CEO of the company, Oscar Munoz, said he was ashamed of the incident after he was the video where the man is seen being dragged by security officers down the aircraft aisle. “It’s not so much what I thought, it’s what I felt. Probably the word ‘ashamed’ comes to mind,” Munoz said in an interview to ABC News aired on Wednesday.

Kentucky physician David Dao was dragged out of the aircraft on Sunday after he refused to deboard the overbooked flight. The incident drew criticism from all quarters after video footage of it emerged. Dao had suffered an injury during the episode too.

“That is not who our family at United is,” Munoz said. “This will never happen again on a United flight. That’s my promise.” He said the security officers will no longer be involved in the process of removing passengers. He said he would look into the incident, which he described as a “system failure”.

Dao’s lawyer moved court on Wednesday seeking direction to the airline and the city of Chicago to preserve the evidence in the case. His team will brief the media about the developments on Thursday.

Four people were asked to leave the aircraft on Sunday. But Dao told the airlines officials that he was a physician and needed to be in Kentucky to see patients on Monday. When he refused to leave his seat, three security officers dragged him out by his arms.

Sunday’s incident comes weeks after the airlines was in the middle of a controversy for barring two girls from boarding a flight because they were wearing leggings.