Brazilian police said Monday that three people have been arrested over the brazen theft of an estimated $30 million worth of gold from Sao Paulo’s international airport last week.

Armed men impersonating federal police entered a warehouse at the airport on Friday afternoon, making off with more than 700 kilograms (1,500 pounds) of the precious metal. No shots were fired.

One of those detained worked at the airport and claimed he had cooperated with the robbers after his family was kidnapped, local media reported.

The gold, which had been en route to New York and Zurich, is still missing.