An employee at the Ming Tombs in Beijing confirmed on Wednesday that some cultural relics had been damaged, possibly during an attempted theft. A resident, surnamed Cui, called police after finding ancient stone steps had signs of forced removal, Beijing News reported.

An employee at the site confirmed the damage.“We’ll enhance surveillance through monitoring cameras and arrange more workers to be on duty over 24 hours,” said the employee, who refused to give his name. However, police said they had not yet received any formal notification of damage.

The tombs, a World Heritage site, are located in the capital’s Changping district in an 80-square-kilometer cemetery of 13 emperors of the Ming Dynasty (1368-1644).