MOGADISHU, Somalia (CNN) -- Gunmen attacked a convoy Sunday in Somalia and took several hostages, including two foreign aid workers from the group Doctors Without Borders.
Medecins San Frontieres workers, shown here, were abducted and released in March in Sudan.
Local staff said a three-car convoy was traveling from Rabbure to Hudur in southwestern Somalia, escorted by local bodyguards, when gunmen seized the group.
The district commissioner of Rabbure said the only people released were elders accompanying the staff, with the local and international staff kept as hostages.
Doctors Without Borders, widely known by its French name Medecins Sans Frontieres, did not immediately release the identities or nationalities of the hostages. MSF is an international medical group that works in more than 60 countries. It says it helps people "threatened by violence, neglect, or catastrophe."
Michel Peremans, international coordinator for operational communications for MSF Belgium, which operates in the region, confirmed that the organization had lost contact with two of its staff in Somalia.
Rabbure is in the Bakole region, which is under the control of the group al-Shabaab, considered a terrorist organization by the U.S. State Department.
Al-Shabaab was once the armed wing of the Islamic Courts Union, which took over most of southern Somalia in the second half of 2006. The United States says the group is affiliated with the al Qaeda terrorist network, and the U.S. backed an Ethiopian invasion that drove the ICU from power in 2006.
The ICU's former leader, Sheikh Sharif Sheikh Ahmed, became president after Ethiopian troops withdrew in January. Al-Shabaab rejected the peace agreement that led to the Ethiopian withdrawal and is now fighting Sheikh Ahmed's government.
Attacks on aid workers in the region are common, and U.N. staff came under attack this year.
In Sudan, on the other side of Ethiopia, four workers from Medecins Sans Frontieres were abducted in March and released a few days later.
All four -- an Italian doctor, a Canadian nurse, a French coordinator and a Sudanese guard -- worked for the Belgian section of the humanitarian organization Medecins Sans Frontieres.
Sudan last month ordered 13 major aid groups to leave the country after the International Criminal Court issued an arrest warrant for President Omar Hassan al-Bashir, accusing him of war crimes and crimes against humanity.
CNN's Mohammed Amin and Carol Jordan contributed to this report.