President Desmond Hoyte called out the army to restore order Monday night after mobs shouting charges of fraud stoned election offices and went on a rampage during Guyana's first national elections since 1985.
A man was shot and killed as he carried a mattress from a wrecked store. Others were wounded.
Hoyte reported disturbances in Georgetown, Berbice in the east and Linden to the south. He told the nation over radio and TV he was aware thousands of eligible voters were disenfranchised after going to vote and not finding their name listed. Voting was for president and the legislature.
Police arrested dozens and appeared to gain control at nightfall. Polls closed at 6 p.m.
Balloting in this South American nation was being monitored by more than 100 foreign observers, including former President Jimmy Carter. No immediate comment came from the observers.
Guyana, the size of Kansas, has about 750,000 inhabitants, most of whom are poor.
The president, seen as an underdog candidate for re-election, represents the socialist People's National Congress. His major rival was Marxist Cheddi Jagan of the People's Progressive Party.
Rioting broke out after thousands of Guyanese, most of them backers of Hoyte's party, massed outside national elections headquarters.