13/04/2017 09:52 BST | Updated 13/04/2017 10:47 BST

United Airlines Passenger David Dao To Sue Airline After Video Shows Him Being Dragged From Plane

Things go from bad to worse for the carrier.

The passenger who was violently dragged from a United Airlines flight has begun legal action over the incident.

Reuters reported that lawyers for David Dao have filed an emergency request with an Illinois state court to require the carrier to secure video recordings and other evidence related to the incident.

The lawyers have also demanded the City of Chicago, which runs O’Hare International Airport, to preserve surveillance videos, cockpit voice recordings, passenger and crew lists, and other materials related to United Flight 3411.

Three airport security personnel have been put on leave over the incident.

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United Airlines CEO Oscar Munoz has apologised for the way David Dao was removed from the carrier 

United Chief Executive Oscar Munoz apologised to Dao, his family and United customers on Wednesday, saying the company would no longer use law enforcement officers to remove passengers from overbooked flights.

He said during an ABC News interview: “This can never, will never happen again.”

Munoz was lambasted for initially appearing to blame Dao, who was apparently knocked unconscious and then dragged down the aisle with his mouth bloodied, as other passengers pleaded for security staff to stop.

He later ran back onto the plane, appearing disorientated and saying “just kill me”. Dao had been randomly selected to be removed from the flight because it was overbooked.

Footage shot by other passengers went viral and triggered outrage around the world.

David Dao was violently dragged from a United Airlines flight

Munoz had initially said, in an internal email leaked to the media, that Dao had been “disruptive and belligerent” and staff were “left with no choice”.

But facing a PR disaster on Tuesday evening, Munoz issued a new statement saying he “continues to be disturbed” by what happened and the airline would “fix what’s broken so it never happens again”.

He called it “truly horrific”.

Dao, described by US media as a doctor from Kentucky, was still in a Chicago hospital on Wednesday.

When asked what his injuries were by local TV station WLKY, simply replied: “Everything.”