The disturbing video of a passenger being forcibly removed from a United Airlines plane after it was overbooked has ignited outrage across the country.

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In the video taken Sunday night, the bloodied passenger, who had apparently been knocked unconscious apparently after his head hit an armrest, is dragged down the aisle.

The passenger was removed just before takeoff from a United flight from Chicago to Louisville to make room for an airline employee.

The plane was overbooked and four United employees needed seats. The flight crew asked for volunteers to take a later flight, but when no one came forward, four passengers were chosen by a computer and told to get off the plane.

They all complied except for one irate man who would not leave his seat.

Passenger Tyler Bridges, who posted a video of the incident on Twitter, told Inside Edition that the man was a doctor who had a professional obligation to stay on board.

"He said, 'No, I’m a doctor. I have to be in tomorrow to see patients. I cannot get off,'" Bridges said.

As the passenger was forcefully removed from the plane, he let out a shriek that left other travelers in shock.

"Everyone on the plane kind of was freaking out," Bridges recalled. "Kids were crying. Everyone was upset [and] really disturbed by the scene. It looked like he was knocked out. Unconscious. He had a bloody nose like his nose was busted, his glasses were off, [and] he was really in rough shape as they pulled him off the plane limp."

@united @FoxNews @CNN not a good way to treat a Doctor trying to get to work because they overbooked pic.twitter.com/sj9oHk94Ik — Tyler Bridges (@Tyler_Bridges) April 9, 2017

The man allegedly returned to the plane and was removed again about an hour later. The plane was then ordered back to the gate, where everyone was told to get off.

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“United made an announcement they had to tidy up the plane after they finally got him off which I think meant clean up some of the blood that had to be there. So ultimately he left on a stretcher," Bridges said.

Karen Schaler, the founder of Travel Therapy who watched the video, told Inside Edition the situation was "horrifying."

“I think when you see this video, I don’t know rules or regulations that talk about someone being forcefully removed," she said. "This is a passenger who paid for a ticket, who was on the flight and if they have to involuntarily bump someone, there has to be questions as to how that is done."

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She added: "It was horrifying to see. You see a lot of incidents where people are unruly or potentially a threat to other passengers and they have had to be forcefully removed but this was just a passenger who paid for his ticket like anyone else."

The aviation officer who was seen dragging the passenger has been placed on leave "pending a throrough review of the situation," the Chicago Department of Aviation said in a statement to the Chicago Tribune.

On Monday, the airline issued an apology for the "upsetting event."

"Our team is working with a sense of urgency to work with the authorities and conduct our own detailed review of what happened," United CEO Oscar Munoz said in a statement.

He added: “We are also reaching out to this passenger to talk directly to him and further address and resolve this situation.”:

United CEO response to United Express Flight 3411. pic.twitter.com/rF5gNIvVd0 — United (@united) April 10, 2017

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