Memorial Day weekend is a time to commemorate men and women who died while serving in the military. People make solemn visits to cemeteries, memorials and battlefields to honor the fallen.

That’s not what took place last week at an important Civil War battlefield in Virginia.

The Petersburg National Battlefield has become an active crime scene after looters dug up a site where more than 1,000 Union and Confederate soldiers died, according to the National Park Service.

“This is an affront to the memory of people who fought and died on this field and it is destruction and theft of history from the American people,” Petersburg National Battlefield Superintendent Lewis Rogers said. “This kind of aberrant behavior is always disgusting but it is particularly egregious as Memorial Day weekend arrives, a time when we honor the memories of our friends and family.”

An initial assessment of the damage identified “a large number of excavations in the park,” the Park Service announced Friday. Park staff came across excavated pits this week.

“Thieves were likely looking for relics on a field where more than 1,000 Union and Confederate soldiers died fighting during the Siege of Petersburg,” the Park Service said in a news release.

Looters targeted an area in the eastern portion of the park, located about 135 miles south of Washington, but the marked graves were not disturbed, CNN reported.

Officials haven’t said exactly what was taken, but they described the incident as “looters steal Civil War history.”

“They are probably doing their homework of the area, probably did research on the Civil War,” Park Service spokesman Chris Bryce told CNN.