Gunmen stole 33 kilograms (72 pounds) of gold worth $650,000 (EUR 470,332) from a mining company near the Arizona border, company officials said Thursday.
Four gunmen barged into the company's offices late Wednesday, took the manager and supervisor hostage and ordered them to open a safe holding the gold bars, which were to be exported to the United States, said Miguel Angel Marin, spokesman for the Cerro Colorado mine, owned by the Canadian firm Sierra Minerals Inc.
The employees were later released outside the mine, located near Trincheras, 140 kilometers (90 miles) south of the Arizona border.
The company said in a news release that the gold took two weeks to produce.
It was the second such robbery in little over a month. On June 6, gunmen stole 21 kilograms (46 pounds) of gold worth US$500,000 (EUR 361,794) from the same mine.
Police said they are investigating but have made no arrests.
Marin said the mine is expected to produce 750 kilograms of gold by the end of 2007.