Police are hunting four tomb raiders who fled after they were caught attempting to break into the grave of tycoon Li Ka-shing's wife. They were spotted at 11pm on Lunar New Year's Day by staff of the Hong Kong Buddhist Cemetery as they attempted to prise open the tomb of Li Chong Yuet-ming. The suspects, who were armed with knives and guns, tied up two cemetery workers and robbed them of cash and valuables before breaking into the cemetery office, for a total haul of $70,000. The tomb was damaged and some of its marble tiling removed. Police officers sealed off the grave yesterday. 'A drill, a shovel and some workmen's gloves were found near the grave, which had been vandalised. We have contacted the [Li] family ... nothing had been stolen from the grave,' a police spokesman said. Two knives and a toy gun were found at the scene. The staff, who live on-site, were returning to the cemetery in Cape Collinson Road, Chai Wan, when they were threatened with knives by the four robbers. The suspects, who spoke with mainland accents, made off with $50,000 in cash and a necklace, mobile phones and wine, together worth $20,000. The employees, aged 51 and 53, freed themselves at about 1.30am yesterday and notified police. One employee suffered minor head injuries after being struck. The raid is not the first on Hong Kong cemeteries. A watch was stolen from the Cape Collinson Crematorium last year and three urns were taken from the Tseung Kwan O Chinese Permanent Cemetery in November.