(CNN)A march honoring Nicaraguans killed in violence surrounding recent anti-government demonstrations also ended in bloodshed Wednesday -- the country's Mother's Day.
Protests on Nicaragua's Mother's Day turn deadly
"We've received grave claims of deaths and serious injuries that resulted from today's violence in Nicaragua," Inter-American Commission on Human Rights (IACHR) Executive Secretary Paulo Abrao tweeted Wednesday.
On Thursday, the Nicaraguan Center for Human Rights released a statement saying 16 people had been killed and 88 injured during the clashes. The march had been promoted as a peaceful demonstration by organizers.
Rights group Amnesty International, which had a delegation accompanying the march, said it "witnessed the chaos caused by the detonation of firearms," and accused police and pro-government groups, known as "Sandinista mobs," of carrying out attacks.
Civil unrest has plagued the Central American country since April, when massive protests broke out over proposed government reforms to the country's social security system.
The protests have left close to 900 people injured and many calling for the resignation of President Daniel Ortega.
But during a separate Mother's Day event organized by government supporters, Ortega said he had no plans to step down.
"Nicaragua belongs to all of us, and we are all staying here," Ortega said to the crowd.
State news site Digital 19 reported two people were killed by "right-wing delinquents" Wednesday.
The government claims 17 people have died since the protests broke out on April 18, but Amnesty International says at least 83 people have been killed.
US Vice President Mike Pence condemned the violence.
"The Ortega government must take immediate action to end this violence and protect the lives and rights of its citizens," he tweeted, while linking to a US State Department statement that called for an independent investigation into the deaths.