Around 20 armed robbers raided a Samsung plant in southeastern Brazil on Monday, leaving with 40,000 smartphones, laptops, tablets and other electronics worth $36 million that were loaded in seven trucks, police said.

The thieves arrived after midnight at the plant in Campinas, a city near Sao Paulo, taking guards and 200 employees hostage, a local police spokesman told AFP.

Witnesses told the G1 news website that the robbers, who had staff ID badges, were not aggressive. They ordered everyone to remove their phones' batteries to prevent them from making calls.

They stayed at the plant for three hours and knew exactly where the most valuable merchandise was located, witnesses said.

Samsung said in a statement that nobody was injured and that the South Korea-based company was cooperating with the investigation. (AFP)