All 11 people aboard a U.N. plane carrying military personnel died Friday afternoon when the aircraft crashed into a mountainside in Haiti, a spokeswoman said.

The victims were from Uruguay and Jordan, said Michele Montas, the U.N. spokeswoman.

The cause of the crash of the Casa C-212 was unknown; an investigation has been launched.

The plane, part of the U.N. mission in Haiti, was doing routine surveillance on the border with the Dominican Republic, she said.

The plane crashed 20 kilometers (12 miles) west of the village of Fonds-Verrettes in an area accessible only by foot, Montas said.

The mission is called the United Nations Stabilization Mission in Haiti, or MINUSTAH