RICHMOND, Va. -- Sources told CBS 6 during a closed session Monday night, Richmond City Council President Michelle Mosby used the word "retarded" directed at Councilman Charles Samuels.

Sources said that this happened during a meeting to discuss training for a city worker.

"The retarded word is something we should not be using," said Zhara Lakhni, who has a son with Down Syndrome.

CBS 6 obtained an email sent by Councilwoman Reva Trammell to Samuels Monday night. Trammell wrote, "Charles, I'm so sorry that the President of City Council Ms. Mosby called you retarded."

Trammell also went on to say she was in shock when she said that and spoke up and said "he is not."

Samuels replied to that email and said "Thanks Reva! I too was very disappointed by her attitude and immature nature in which she handled things."

Jamie Liban, executive director of The Arc of Virginia, a well-known nonprofit that advocates for people who are intellectually and developmentally disabled, isn't involved in the incident, but agrees the word is derogatory.

"It is equally as offensive to people with intellectual disabilities and their families as other derogatory terms for other communities," she said.

CBS 6 reached out to Mosby for comment. She insisted that she never called any of her colleagues by any name other than their own, or their titles.

However, when asked if she used the term "retarded" at all in the conversation, she refused to answer and said she would not talk about things said in closed session.

Regardless of how it may have been said, Lakhni said it's a word that should be banned from everyone's vocabulary.

"Using those words, even though people are not hearing it and you're just saying it to each other in a closed room, that doesn't mean it's appropriate," she said.

CBS 6 also reached out to Samuels about the alleged incident.

In a statement he said "Because I believe it's important to have frank, open, and honest discussions between council members, it's my policy not to discuss what is said during closed sessions."

We also reached out to Trammell for comment regarding the email obtained. Trammell said she had no comment at this time.