(CNN) Cincinnati Mayor John Cranley apologized after his office inadvertently issued a proclamation honoring a man who ambushed and killed a Cincinnati police officer.
"I am really sorry that my office, that we mistakenly issued a proclamation on behalf of a man that killed, murdered Sonny Kim," Cranley said Thursday night.
Cranley choked back tears as he spoke at a local police union hall. His face was red as he paused several times during his brief, tear-filled statement.
"He was a hero," Cranley said about Kim, a father of three, who was fatally shot in June 2015.
Kim had responded to a 911 call after Trepierre Hummons, 21, contacted emergency operators twice that day, pretending to be a concerned witness who had seen a man acting erratically with a gun. When Kim arrived on scene, he was shot multiple times by Hummons, according to police. Hummons opened fired at two more officers before he was shot and killed.
Last week, the mayor's office received a request for a proclamation from Ronald Hummons for his son's birthday. The request didn't contain his son's full name and the staff member reviewing the request wasn't aware that the man being honored had killed Kim, according to the mayor's letter of apology to the Cincinnati Fraternal Order of Police.
A staff member wrote the proclamation, granting June 1, 2017, "Tre Day" in Cincinnati. The proclamation was then approved by the communications director.
"Neither of them looked further into the context of the proclamation," stated the mayor's letter, which was carried by CNN affiliate WCPO. "They were both unaware that TrePierre was the man who murdered Sonny Kim."
Once the mayor's office became aware of the mistake, it retracted the proclamation.
"This was a huge mistake," Cranley said. "It was not done intentionally. It was a human error, but the buck stops with me."
The mayor said he apologized to Kim's widow, the Cincinnati Police chief and the officer who returned fire when Kim was shot. Cranley voiced his support for the police department, got choked up and stepped away from the podium.
Cincinnati Fraternal Order of Police President Dan Hils said he felt sick when he heard about the proclamation, but that Cranley appeared to own up to the error.
"He's supportive of law enforcement," Hils told WCPO regarding the mayor. "This was a breakdown in his office. I'm very glad that he said he was taking responsibility for it. I believe real leaders do that even in the worst of times."