Limbert Guzman, a 20-year-old student, died late Wednesday in a clinic in the city of Cochabamba following clashes between supporters and foes of President Evo Morales. About 90 people were also injured.
The U.N. office in Bolivia called on authorities to investigate in a statement that condemned "intolerance and violence" in Bolivia. "Nothing justifies clashes between Bolivians, and the death of citizens is unconceivable," the U.N. statement said.
Morales expressed his condolences on Twitter. Bolivia's first indigenous president said Guzman had been a victim of violence promoted by political groups that encourage racial hate. Opponents challenge an official count that showed Morales winning by a margin big enough to avoid the need for a runoff against a united opposition. Morales accuses the opposition of trying to stage a coup.
Two people were fatally shot last week during clashes in Santa Cruz province, an opposition bastion. The demonstrations continued in most cities on Thursday. Protesters marched and set up barricades to block roads.
Opposition leader Luis Fernando Camacho, who has been leading protests in Santa Cruz, arrived in the capital of La Paz. He planned to try to deliver a letter to Morales demanding his resignation. A delegation from the Organization of American States is in Bolivia carrying out an audit of the election. The results are expected next week.
The opposition, led by former president Carlos Mesa, rejects the audit. He says its terms were agreed upon "unilaterally" by the government and the OAS, without consulting the opposition or other civil society groups.
Mesa came less than one percentage point away from forcing a runoff against Morales, who has been in power for 14 years. Suspicions about possible electoral fraud arose following a 24-hour halt in the reporting of vote results.
Voters have been angered by Morales' refusal to accept the results of a 2016 referendum to keep limits on presidential terms. A subsequent decision by the country's top electoral court allowed him to seek a fourth term.