Police have been caught in the middle as rival party supporters clash
At least two people have been killed and six others injured in Nicaragua in post-election violence, according to unconfirmed reports from the country.
There was gunfire as supporters and opponents of the governing left-wing Sandinista party clashed after nationwide municipal elections.
The opposition and monitors alleged voting irregularities.
But President Daniel Ortega, whose party claimed victory based on partial results, denied voter fraud.
The US criticised Mr Ortega's government for barring international monitors' access to Sunday's poll.
With the majority of votes counted in 146 municipalities, the Sandinistas were leading in most of the major races.
Current partial results show the governing party's candidate, former boxing champion Alexis Arguello, leading in the hotly-contested race to be mayor of the capital, Managua.
The mayoral race in the capital Managua has been hotly fought
But in an BBC interview, opposition politician Eduardo Montealegre claimed victory in the contest for the keys of city hall.
The former finance minister, who lost the 2006 presidential election to Mr Ortega, said he would demand a recount if he lost.
It was the first major electoral test for President Ortega since he was re-elected president in 2006, nearly two decades after leading a Marxist government that fought US-backed Contra rebels.
Having refused to accredit election observers, Mr Ortega, an enduring critic of US foreign policy, claimed the monitors were "financed by outside powers".
The civic group Ethics and Transparency, which was among would-be election observers denied accreditation by the government, said it had nevertheless recorded irregularities in 32% of the polling places it monitored.
In Washington, state department spokesman Robert Wood said "political conditions that existed during the campaign were not conducive to free and fair elections".