The city of Cleveland apologized on Thursday for its role in preparing a $500 ambulance services claim against the estate of 12-year-old Tamir Rice, who was fatally shot by police in 2014, and said it had dropped the demand.

City officials said a claim had actually been filed in probate court and that it had now been withdrawn. They said they never intended to bill the Rice family, according to a statement from Mayor Frank Jackson.

The invoice, dated Wednesday, is for Rice's "last dying expense" and included $450 for an ambulance and $50 for mileage, according to city documents.

"Again, apologizing to the Rice family if in fact this has added to any grief or pain that they may have," Jackson told reporters.

Rice, a black child who was playing with a replica gun in a park, was shot by a white police officer. The child's death helped fuel the national debate over police use of deadly force, especially against minorities.

After the Rice killing, a U.S. Justice Department investigation found widespread excessive use of force by Cleveland police. The next day, the Rice family filed a federal civil rights lawsuit against the city and officers involved.

In January 2015, the city received a partial reimbursement from Medicaid for $172.90 for ambulance services for Rice, the statement said. The remaining $327.10 was absorbed by the city and the matter closed, the city said.

Earlier this week, the executor for Rice's estate asked the city to provide a billing statement for services provided to Rice.

When the city got the request, the bill was opened again and sent to the executor, Jackson's office said. Following standard procedure, a city attorney filed a claim with the probate court for $500 against the Rice estate. On Thursday, the city withdrew its claim.

Jackson said "red flags should have risen" to prevent the claim from being filed.

"But that didn't happen. Did anybody do anything wrong in this? No, because it's the normal process."

Rice family attorney Subodh Chandra said in a statement that the claim made no sense to the family. "This adds insult to homicide."

A grand jury in December declined to bring criminal charges against the officers involved in the shooting.

Earlier on Thursday, U.S. Democratic presidential candidate Hillary Clinton tweeted: "Asking Tamir's family to pay for his ambulance is heartless. Cleveland should drop this fee."