Brazzaville, Congo Republic ? Congolese voters appeared to be deeply divided in Sunday’s historic election, casting ballots along geographic lines and possibly sending the presidential contest into a runoff, according to analysts studying partial returns.

The picture they offered in interviews was of a two-candidate race, with incumbent President Joseph Kabila winning in Congo’s densely populated east and Jean-Pierre Bemba, a former rebel leader and one of four vice presidents, winning in the capital, Kinshasa, and other western areas.

Results in the broad middle of the nation were less clear, with other candidates making strong showings in some places. The ballot included more than 30 candidates. At least five received significant vote totals, analysts said, and if no candidate gets a majority of 50 percent, the top two finishers will face each other in a runoff on Oct. 29.