KIGALI, Rwanda  A mayor who was indicted for orchestrating the massacre of more than 2,000 Tutsi seeking refuge in a church during the 1994 genocide in Rwanda was captured and arrested this week in eastern Congo after 15 years in hiding, according to Congolese officials.

The fugitive, Grégoire Ndahimana, who is wanted for genocide and complicity in genocide, was arrested in North Kivu Province late Tuesday evening by Congolese armed forces. He had been fighting in eastern Congo with the Democratic Forces for the Liberation of Rwanda, or F.D.L.R., a primarily Hutu rebel group of genocide committers and other combatants who are now stirring chaos in Congo’s troubled east.

Congolese officials said the fugitive was caught by surprise. “He was captured while he was coming to look for some food within the local population,” Olivier Hamuli, a spokesperson for the national army, said via telephone.

Both Rwanda and Congo called the capture one of the most significant achievements to date of the joint military operations being undertaken by the two countries against rebels in the area.