A postal worker was fatally shot on Friday night in Milwaukee while delivering mail, police said.

The victim was a 44-year-old man who had been with the U.S. Postal Service for 18 years. His name has not yet been released.

“The Milwaukee Police Department sends our sincere condolences to the victim’s family and to the USPS for the loss of their member,” the police department said in a statement.

The situation unfolded around 5:59 p.m. on Friday when Milwaukee police responded to an injured person in the 5000 block of N. 65th Street. When they arrived, officers found the victim with a gunshot wound. He was pronounced dead at the scene by the Milwaukee Fire Department.

Milwaukee Mayor Cavalier Johnson said on Twitter that “The shooting death of a Milwaukee postal worker is alarming. My thoughts are with the victim’s family and colleagues. The postal worker in this homicide was a public servant, which makes this crime even more disturbing.”

The circumstances leading up to the shooting are under investigation by Milwaukee police, with the help of the U.S. Postal Inspection Service and the FBI.

“Initial information received from local law enforcement indicated a USPS letter carrier was shot and killed while delivering mail,” the U.S. Postal Inspection Service said in a statement. “The safety and security of Postal employees is a top priority of the U.S. Postal Inspection Service.”

Anyone with information should call Milwaukee police at (414) 935-7360 or Crime Stoppers at (414) 224-TIPS.