The “Back the Blue” mural that appeared in front of Tampa’s Police Department headquarters was vandalized with red paint and tar, city officials said Wednesday.

A video from WTVT showed splashes of red paint and tar across the mural. The Tampa Bay Times reported that much of the vandalism appeared to cover the word “blue.” It is unclear at this point who damaged the mural.

A spokesperson for the city of Tampa said the vandalism took place overnight but did not have any other comment, including whether the police were investigating the incident.

A group of about 40 volunteers painted the “Back the Blue” street mural Saturday night outside Tampa’s police headquarters.

The group said they wanted to boost police morale, even though it was painted before they got a permit.

Keith Campbell, who organized the painting, told WTVT that his group obtained verbal approval from the mayor’s office. But a spokesperson for the mayor says the city was going through the formal process and the steps needed to obtain formal permission were not complete.

“Any tribute to honor their service is welcome. It’s unfortunate they didn’t see the permitting process through so that our community could participate in showing their appreciation for the brave men and women that service our residents every day,” said Mayor Jane Castor.