Brazil-based Vale announced Friday that the railroad that links the company's Carajas iron ore mine (the largest in the world) with a port terminal in northeastern Brazil was shut down after a partial derailment early Friday morning.

The incident, which took place in Maranhao state, involved 11 of the train's 30 cars--it was not reported whether the affected cars were carrying iron ore at the time, or how long the shutdown would last.

The 892-kilometer (554-mile) railway connects the mine, which produced 106.8 million metric tons of ore in 2012 (33 percent of Vale's total output), to Maranhao's Ponta de Madeira port.