A memorial in Philadelphia to honor American military service members who fought and died while serving in Vietnam was vandalized, caretakers said. 

Terry Williamson, president of the Philadelphia Vietnam Veterans Memorial, vandals caused $20,000 in damage, the most significant damage in the memorial's 36-year history. 

"It just seems that for every two steps forward we take, these thugs and miscreants set us back three steps," he said in a statement. "The PVVM board was planning to take on a number of maintenance projects, including the repair of dangerous and severely damaged walks in the area of the Memorial. That will need to be put on hold."

The damage includes destroyed light fixtures, ripped-off medal medallions and skate guards. Damage to the marble is still being assessed. 

The incident occurred sometime within the past four or five days, Williamson said.

Caretakers plan to raise funds to repair the damage, which includes 20 "Star" skate toppers pried off the marble and 10 recess light covers and some light fixtures removed or smashed. 

The memorial bears the names of 648 native Philadelphia natives who died in the Vietnam conflict, similar to the Vietnam Veterans Memorial in Washington D.C.