DAKAR (Reuters) - Six Red Cross volunteers were killed in an attack on a health center in southeast Central African Republic on August 3, the aid organization said in a statement on Wednesday.

Civilians and medical staff may also have been killed in the attack, by unknown assailants, the Red Cross said, adding that more details were not yet available.

Militia violence has intensified in southeast Central African Republic this year, including attacks on peacekeepers and aid workers, prompting fears of a possible return to large-scale chaos that gripped the country at the peak of a 2013 civil war.

The six volunteers killed were all from Central African Republic and were participating in a crisis meeting at a health center in the town of Gambo, in the Mbomou prefecture, the Red Cross said.

It was the third attack on Red Cross workers in Central African Republic this year, which include the shooting in June of one worker in the diamond-mining town of Bangassou, about 100 kilometers (62 miles) away.