Embarrassing viral videos of a bloodied man being forcibly dragged off a United Airlines flight departing O’Hare Airport have resulted in a Chicago Department of Aviation security officer being placed on paid leave.

“The incident on United flight 3411 was not in accordance with our standard operating procedure and the actions of the aviation security officer are obviously not condoned,” Aviation Department spokeswoman Karen Pride said. “That officer has been placed on leave effective today pending a thorough review of the situation.”

United was trying to make room for four employees of a partner airline on the overbooked Sunday evening flight to Louisville. When no one volunteered, a United manager came on the plane and announced passengers would be chosen at random, including the unidentified man who was dragged off, according to passengers.

United employees had no choice but to contact authorities to remove the man, an airline spokesman said.

Officers grabbed him from a window seat of the United Express jet, pulled him across the armrest and dragged him down the aisle by his arms.

Social-media videos of the incident were drawing worldwide attention. One 31-second clip posted on the Facebook page of Audra D. Bridges had more than 7.8 million views as of Monday evening.

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“United airlines overbooked the flight. They randomly selected people to kick off so their standby crew could have a seat,” Bridges wrote on Facebook. “This man is a doctor and has to be at the hospital in the morning. He did not want to get off.”

Multiple passengers exclaimed “Oh my God!” as the man screamed.

Passenger Jayse Anspach tweeted: “It looked like he was knocked out, because he went limp and quiet and they dragged him out of the plane like a rag doll.”

On Monday morning, United CEO Oscar Munoz said on Twitter, “This is an upsetting event to all of us here at United. . . . Our team is moving with a sense of urgency to work with the authorities and conduct our own detailed review of what happened. We are also reaching out to this passenger to talk directly to him.”

Chicago has two law-enforcement forces that patrol O’Hare and Midway airports: the Chicago Police Department, whose officers are armed, and Department of Aviation police, whose officers are unarmed. Aviation officers alone handled the situation aboard the United flight.

Despite this, a Chicago Police news affairs officer — not the aviation cops — initially released a statement to an unnamed media outlet saying that a “69-year-old male Asian airline passenger” became “irate” aboard the flight and that aviation officers “attempted to carry the individual off the flight when he fell.”

As the Chicago Police statement began circulating on Twitter — with people taking exception to the characterization that the man “fell” — police said that any further information should come through the Department of Aviation.

Pride couldn’t explain why only one aviation officer is targeted for disciplinary action when other officers were at least tangentially involved in the incident.

Responding to the incident, the U.S. Department of Transportation said it is reviewing United’s “involuntary denied boarding” of the man, and whether United complied with consumer protections regulations, including its over-sales rule. “While it is legal for airlines to involuntary bump passengers from an oversold flight when there are not enough volunteers, it is the airline’s responsibility to determine its own fair boarding priorities,” the department said.

United couldn’t secure enough volunteers to leave the overbooked flight, said Audra Bridges’ husband, Tyler Bridges. He said United offered $400 and then $800 vouchers and a hotel stay for volunteers to give up their seats.

When airline employees named four customers who had to leave the plane, three of them did so. The fourth refused to move, and law-enforcement officials were called, United spokesman Charlie Hobart said.

“We followed the right procedures,” Hobart said. “We wanted to get our customers to their destinations.”

After dragging the man off, the four employees of the partner airline boarded. “People on the plane were letting them have it,” Bridges said.

A few minutes later, the man who was removed from the plane returned, looking dazed and saying he had to get home, Bridges said.

Officers followed him to the back of the plane. Another man traveling with high school students stood up at that point and said they were getting off, Bridges said. About half of the passengers followed before United told everyone to get off, he said.

The man who was originally dragged down the aisle was removed from the plane again, and United employees made an announcement saying they had to “tidy up” the aircraft, Bridges said.

Aviation industry expert Robert W. Mann Jr. watched the video and said he had never seen anything like it.

“I’ve never seen a passenger forcibly removed unless it involved an unruly passenger of some sort,” he said.

“What I would have asked the passenger is ‘Why not? Why can’t you do this? Can you give me a really good rational reason?’ And if he could, then we try to find one more volunteer. I think I would have gone to round two of the selections,” Mann said, adding that airline employees probably had a ceiling on how much they could sweeten the cash offer to incentivize volunteers.

“At the very least, it’s a teachable moment for the airline,” Mann said.

A spokesman for Service Employees International Union Local 73, which represents Chicago’s aviation security officers, said “the incident that occurred on United Flight 3411 was an unfortunate one. We are aware the Chicago Department of Aviation is investigating the incident, and we will reserve further comment until the investigation is completed.”

Contributing: Associated Press, Mitch Armentrout