(CNN) More than 25 years ago, two Baton Rouge police officers wore blackface for an undercover operation. This week, the Louisiana city's police chief apologized after a photograph of the officers from a department yearbook surfaced online.

The photograph from 1993 showed two white officers in blackface wearing sunglasses with the caption "Soul brothers." One officer had his arms crossed; the other made hand signs.

The image first surfaced in the Rouge Collection, a local news site, according to The Advocate, a Baton Rouge newspaper that published a story on Monday.

Police Chief Murphy Paul and the city's mayor on Monday condemned the blackface.

Paul said the photograph was taken when the officers were taking part in a "department-approved" operation.

"Blackface photographs are inappropriate and offensive. They were inappropriate then and are inappropriate today. The Baton Rouge Police Department would like to apologize to our citizens and to anyone who may have been offended by the photographs," the chief said.

Paul did not name the officers in the photograph.

A national reckoning on blackface

The 1993 photograph has surfaced amid a national conversation about the racist and painful history of blackface.

The origins of blackface date back to minstrel shows of the mid-19th century. White performers darkened their skin with shoe polish and burnt cork and put on tattered clothing, exaggerating their features to look stereotypically "black." The first minstrel shows mimicked enslaved Africans on Southern plantations, depicting black people as lazy, cowardly, ignorant or hypersexual, according to the Smithsonian's National Museum of African American History and Culture

The performances were intended to be funny for white audiences.

American actors and comedy partners Charles Correll (L) and Freeman Gosden lean against each other in blackface makeup in a 1949 promotional portrait.

There are several recent controversies involving blackface.

Democratic Virginia Gov. Ralph Northam is facing calls to resign after a photo surfaced earlier this month of a man in blackface and another man in Ku Klux Klan garb on Northam's page in a 1984 medical school yearbook.

Northam initially apologized for the photo, saying it was him, without specifying which person he was. The next day, he said he wasn't in the photograph, but admitted that he once wore blackface in the 1980s when entering a dance contest dressed as Michael Jackson.

Days later, Virginia Attorney General Mark Herring said he appeared in blackface at a 1980s party. He said some friends suggested showing up like rappers they listened to at the time, such as Kurtis Blow.

Last month, University of Oklahoma students were involved in a video showing a woman in blackface and possibly using a racial slur. The university said the students involved "will not return to campus." This week, singer Katy Perry, who also designs a line of shoes, discontinued a design that some internet commenters considered evocative of blackface. And Gucci pulled an $890 sweater from its line and apologized after it was criticized as resembling blackface.

"Blackface is more than just a costume. It invokes a painful history in this country and it is not appropriate in any situation," Baton Rouge Mayor-President Sharon Weston Broome said in a statement.

'We would not allow our officers to wear blackface'

Paul said the department cannot apply its existing policies to conduct that occurred before those policies were implemented.

"Today, we would not allow our officers to wear blackface in an official capacity under any circumstances," he said. "We have policies in place to prevent our officers from engaging in this type of behavior both on and off-duty."

In an interview with CNN, Greg Phares, who was Baton Rouge's police chief at the time of the operation, rejected the term blackface in relation to the photo. He said the officers were attempting to blend in to a black community during a legitimate undercover operation to crack down on drugs and crime.

He said the department used black officers in some undercover operations, but they were recognizable to the black community because of their work, making undercover work in that community dangerous for them.

Seven undercover police officers were involved in the operation, according to The Advocate.

"I did not have a problem with it then. I do not have a problem with it now," Phares said. "It was done to do good police work."

He added: "It was not done to degrade anyone or to make fun of anyone."

'As we know more, we will do different'

Maxine Crump, CEO and president of Dialogue on Race Louisiana , which seeks to eradicate racism, said those who wore blackface years ago likely believed it wasn't offensive because it was part of the common narrative.

"However, the question becomes today when they're confronted with it, what they say then is what they're being judged by," Crump said in an interview late Tuesday.

She said the officers likely didn't ask themselves about the harm they were causing the black community with the "disrespectful image."

"They didn't have to ask how are black people going to feel? They decided it was more important to score a good value for police work ... rather than think about the harm they could've been bringing to that community."

Crump said she is excited "that anything that has been so subtle and underground about racism is coming to the surface."

"As we know more, we will do different," she said.