Thousands of U.N. peacekeepers are stepping up security ahead of Sunday's historic presidential runoff vote in Central African Republic.

White trucks coated in red dust snaked through the capital Saturday delivered voting materials to polling stations in Bangui, the capital, on Saturday.

Voters will choose between two former prime ministers who emerged from the first round of balloting in December.

Central African Republic descended into sectarian violence in late 2013 and nearly 1 million people have been displaced by the fighting between Muslim and Christian militias.

Tens of thousands of voters are casting ballots from refugee camps in neighboring Cameroon and Chad.

Both candidates have campaigned on messages of peace and unity. The country has been led by a transitional government for the past two years.