There are conflicting reports about threatening comments a police officer may have made about first lady Michelle Obama, the District of Columbia police chief said Friday. The department and the Secret Service are investigating an allegation of what it says were "inappropriate comments" about the first lady, allegedly made this week by a city officer who worked as a member of a motor escort for the White House. Police Chief Cathy Lanier told The Associated Press in an email that there are "conflicting reports about what was said." Although it's not clear how seriously the comments were meant to be taken, the officer has been put on administrative duty while authorities investigate, Mayor Vincent Gray said. "We don't know whether there's any truth to this or not, but it's obviously serious enough to warrant a very intense ... investigation," Gray said while appearing as a guest on NewsChannel 8's weekday political show. The Washington Post cited anonymous police officials in reporting the officer told colleagues he would shoot the first lady, and then showed a photo on his phone of a gun he would use. "It's hard to believe that a police officer would do something, say the kind of things" that were alleged, Gray said. But, he added, "there's no room for jokes or frivolity when you're dealing with the first family." Secret Service spokesman Edwin Donovan said the agency was aware of the report and was taking "appropriate follow-up steps." A White House spokesman said President Barack Obama was aware of the investigations but had nothing to say about it, and he referred questions to the Secret Service. Typically, in the case of a threat against a member of the first family, the Secret Service interviews participants and witnesses and then decides how to proceed.