Mayor Kasim Reed is vowing to fire any city employee who had a role in an embarrassing photo scandal in which an Atlanta fire station was used as a backdrop for escort advertisements.

“We’re going to fully investigate it, get to the bottom of it, and fire the people involved,” Reed said on Thursday.

Earlier this week, photos of at least three women in suggestive poses and wearing Atlanta Fire Rescue gear, appeared on the website Backpage.com. Backpage, an online classifieds portal, advertises escort services and has been accused of facilitating sex trafficking.

Reed said he’s concerned that “folks who have a sacred duty” allowed public facilities to be used in a way that is “inappropriate and demeaning to women.” The women depicted in the photos are not city employees.

“Everybody who is involved in this process is going to be dealt with swiftly and severely upon conclusion of this investigation,” Reed said. It’s unclear how long the probe will take.

One firefighter has already been placed on paid leave over the incident. Lt. Jathan Dortch told the television station WXIA that he doesn’t know exactly what led to at least one of the women posing on a fire truck, nor did he know the photos would be used to advertise escort services.

Vic Bennett, vice president of the Atlanta Professional Firefighters Association, said firefighters are trained to welcome curious citizens and that stations often serve as safe havens. It’s common practice to allow citizens to take photos with firefighters and equipment, he said.

Bennett said union leadership is “extremely disturbed” by the photos, but doesn’t believe that firefighters participated in their taking or were aware of their intended use. One of the women claimed to be the daughter of a retired firefighter from the station in question, Bennett said. A firefighter asked the women to leave after noticing one of them posed in an “inappropriate manner.”

He’s worried that Reed has already made up his mind about the outcome of the probe, he said.

“The fact that the mayor said he was going to fire the person involved tells us there will not be a vigorous or consistent investigation,” he said.