Six civilians and a rebel fighter were killed overnight during an attack by the ADF armed group in the troubled east of the Democratic Repulic of Congo, civilian and military sources said on Tuesday.The attack in the town of Oicha sparked a protest by several thousand conflict-weary residents of nearby Beni, the scene of frequent raids blamed on the Allied Democratic Forces, a Ugandan jihadist group."The ADF raided overnight Monday," Beni administrator Donat Kibwana told AFP. "They were repelled by the army but unfortunately they killed six civilians, and the army killed one ADF (fighter)."Army spokesperson Captain Mak Hazukay confirmed the death toll from the attack, which comes less than four weeks before crucial elections set for December 23 in the vast former Belgian colony.Jonas Mbulete, a resident of Oicha, which is around 30km north of Beni, said the assailants burned five homes.Two other people died on Monday during a separate attack blamed on the ADF.The army of the Democratic Republic of Congo and troops of the UN peacekeeping mission MONUSCO began a joint operation against the group two weeks ago.Marchers on Tuesday carried banners reading "Enough is enough" and bearing slogans in support of the army and MONUSCO.Beni has also borne the brunt of an Ebola outbreak that has claimed 240 lives as of the last health ministry bulletin on Monday.The ADF started out in 1989 with the aim of overthrowing Uganda's President Yoweri Museveni, who was seen as hostile to Muslims. But it went on to absorb other rebel factions into its ranks and started carrying out attacks in 1995. Forced westwards by the Ugandan army, the group relocated most of its activities to the DRC, finding a lucrative niche in the vast central African country's lawless, resource-rich east.Numerous other armed groups operate in the region, wreaking havoc in the decades since the official end of a 1998-2003 war which claimed millions of lives.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.