CLEVELAND, Ohio -- Cleveland Mayor Frank Jackson on Monday issued an apology to the family of Tamir Rice, stating that city lawyers used insensitive language in answering a lawsuit filed after the 12-year-old was shot and killed last November by a Cleveland police officer.

During a news conference at City Hall, Jackson said the city's Law Department was trying, in good faith, to protect the city's legal position in a wrongful death lawsuit filed by Tamir's family. But the lawyers, Jackson said, used language that violates the values of the city and his administration.

"To protect our defenses, we used words and phrased things in such a way that was very insensitive to the tragedy in general, and to the victim in particular," Jackson said. "It is not part of the character of the city of Cleveland and this administration. We are apologizing to the family and to the citizens of Cleveland for our poor use of those words and our insensitivity."

The boy's mother, Samaria Rice, and the family's attorneys have scheduled a news conference for 11 a.m. Tuesday to issue a response.

The city's response stated that Tamir's death and all of the injuries his family claims in the suit "were directly and proximately caused by their own acts, not this Defendant."

It also says that the 12-year-old's shooting death was caused "by the failure ... to exercise due care to avoid injury."

The response did not explain the defenses in more detail, though 20 defenses are listed in all, including another one that says Tamir died because of "the conduct of individuals or entities other than Defendant."

Law Director Barbara Langhenry, who acknowledged at the news conference that she signed off on the city's response, said the city has 21 days to amend it.

The lawyer who wrote the document was using a routine defense against such claims, Langhenry said, adding that the city will continue to aggressively defend itself in the case, while exercising greater sensitivity from now on.

Jackson said he found out Monday morning about the language used, after news reports on the court filing went viral over the weekend.

He said he questioned Langhenry and immediately decided that Tamir's family deserves an apology. Jackson said he reached out to the family's attorney, Walter Madison, who was "gracious and understanding and accepting and communicated to the family our apologies."

When asked if the mayor is also apologetic about the shooting outside of the Cudell Recreation Center on Nov. 22, Jackson replied: "I'm on the record regarding what happened at Cudell. There is no way that a 12-year-old should die."

Minutes later, the mayor became emotional, as he explained how personally he took the news of Tamir's death.

"I have a 12-year-old grandson who is about that tall," he said, his hand hovering near his shoulder. "I have an 18-year-old grandson and a 9-year-old and a 3-year-old."

Jackson's eyes welled with tears, and he stood silently for a moment.

"And it's difficult for me to ... to imagine that."