The struggle to contain an Ebola outbreak in the Democratic Republic of Congo (DRC) suffered another setback on Thursday when a treatment center came under attack from protesters enraged by the cancellation of Sunday’s presidential vote in the city of Beni.

According to the DRC health ministry, 24 patients fled from the center during the chaos. Of those who fled, 17 had reportedly tested negative for Ebola and three of the patients returned to the clinic once guards restored order. The ministry has contact information for all of the other patients and is attempting to get them back.

According to officials at the Ebola treatment center, protesters attempted to force their way inside but were repelled by U.N. peacekeepers. Police and military forces also dispersed a group of protesters who tried to force their way into the local offices of the national election commission.

Australia’s ABC News reported on Thursday that the election in Beni was ostensibly canceled because of the Ebola outbreak and local violence, but opponents of President Joseph Kabila suspect he opportunistically used the medical situation as an excuse to shut down voting in an opposition stronghold and swing the election to his chosen successor, former interior minister Emmanuel Ramazani Shadary. Health officials had given explicit assurances the election would not be affected by the disease outbreak.

The presidential election, which would mark the first transfer of power since Kabila took office in 2001 following the assassination of his father, has already been postponed for two years. Voters in the politically restless and Ebola-stricken province of North Kivu have now been told they have to wait until at least March to cast their ballots, even though the winner of the election will be announced on January 15 and inaugurated three days later. Furious opposition leaders called the situation “unacceptable” and said the delayed, ultimately meaningless election will effectively disenfranchise over a million voters.

Political activists said they have campaigned actively in the outbreak area without suffering any Ebola infections, children are still going to school, and most civic activities continue as normal, so there is no reason to delay the vote. Health officials are worried about reports that some Congolese think there is no Ebola outbreak at all, just a conspiracy by Kabila’s government to declare a phony health emergency so he can suppress opposition voters.