CHICAGO (AP) — The Chicago Department of Aviation has fired two security officers involved in an incident in which a passenger was dragged off a United Airlines flight after refusing to give up his seat, the city's Office of Inspector General said in a report released Tuesday.

One of the fired officers, a sergeant, also was part of an attempt to cover up some details of the incident that happened in April at Chicago's O'Hare International Airport, according to the report.

Four officers were involved in the confrontation with passenger David Dao, who was aboard a flight to Louisville, Kentucky. The Aviation Department suspended the two other officers — one for five days and the other for two. The officer who received the five-day suspension resigned.

The Office of Inspector General said in the report that as a result of the office's findings and recommendations, the Aviation Department fired an officer who "improperly escalated the incident" and a sergeant involved in removing facts from a report. The inspector general report does not identify the officers.

The report says the investigation by the Office of Inspector General found three security officers and a sergeant used excessive force and "made misleading statements and deliberately removed material facts from their reports" on the April 9 incident.

"The use of excessive force caused the passenger to hit his face on an armrest, resulting in a concussion, a broken nose, and the loss of two teeth," the report said.

Dao, a physician who was 69 at the time of the incident, reached an undisclosed settlement with United less than three weeks after the incident.

The incident aboard United Express Flight 3411 was videotaped by other passengers and widely shared online. It became an international embarrassment for the airline and the Aviation Department.

A report released by the Aviation Department in April in response to a Freedom of Information Act request by The Associated Press identified the officer who pulled Dao out of his seat as James Long. It's not clear if Long lost his job or was suspended, because the inspector general report doesn't name the officers.

The Aviation Department also confirmed that a review of its policies and procedures is underway and will be finished by the first quarter of 2018. In reaction to the Office of Inspector General recommendations, the department also wrote a statement of intent that makes it clear that the Aviation Security Division provides security services for airport staff and passenger safety, not police services.

Dao's attorney, Thomas Demetrio, told The Associated Press on Tuesday that they were not expecting the dismissal of the security officer who is not a sergeant, but said it may resonate with others.

"In firing him, perhaps it will send a clear message to police and airline personnel all over the world that unnecessary violence is not the way to handle passenger matters," Demetrio said.

He said it surprises him that the Aviation Department's review of its policies and procedures isn't complete.

"That should have been done the next day," the lawyer said. "It seemed to me the policies and procedures would have been tweaked the next day."