Baltimore police have launched an investigation after a sign was discovered on the inside of the rear door of a police van that apparently taunts prisoners with the message, "Enjoy your ride, cuz we sure will!"
The message is especially inflammatory as its discovery was made in the wake of the death of Freddie Gray, a black man who suffered a severe spinal cord injury while being transported in the back of a police van in April and later died.
Gray was handcuffed but was not restrained by a seat belt after he was placed in the police van after his arrest on April 12, police have said. He died of the spinal injury on April 19.
"The nature and the posting of wording in one of our transport vehicles is both concerning and unacceptable," the Baltimore Police Department said in a statement. The sign was first reported by NBC affiliate WBAL.
Gray's death touched off protests and riots, and six Baltimore police officers have been charged in his death. It is unclear how long the message has been on the inside of a rear door of the van.
An autopsy reportedly found that Gray's fatal injury was most likely caused by a sudden change of speed of the police van. The autopsy's conclusions were reported by The Baltimore Sun on June 23.
This article originally appeared on NBCNews.com.