Passengers on a United Express flight from Chicago to Louisville, Ky., were horrified when a man was forcibly removed--violently wrenched from his seat and physically dragged down the aisle. [...] Videos of the scene have prompted calls to boycott United Airlines.

[...] The Chicago Department of Aviation [...] says the actions of the security officers were "not condoned by the Department" and that one individual has been placed on leave pending a review.

[...] Passengers had already boarded on Sunday evening [April 10] at O'Hare International Airport when United asked for volunteers to take another flight the next day to make room for four United staff members who needed seats.

The airline offered $400 and a free hotel, passenger Audra D. Bridges told the Louisville Courier-Journal. When no one volunteered, the offer was doubled to $800. When there were still no bites, the airline selected four passengers to leave the flight--including the man in the video and his wife.

"They told him he had been selected randomly to be taken off the flight", Bridges said.

[...] The man said he was a doctor and that he "needed to work at the hospital the next day", passenger Jayse D. Anspach said.

[...] Both Bridges and Anspach posted videos of three security officers, who appear to be wearing the uniforms of Chicago aviation police, wrenching the man out of his seat, prompting wails. His face appeared to strike an armrest. Then they dragged his limp body down the aisle.

Footage shows the man was bleeding from the mouth as they dragged him away. His glasses were askew and his shirt was riding up over his belly.

"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", Anspach wrote.