Non-governmental organizations and hospital sources say 13 people have been killed in attacks on demonstrators in Nicaragua's capital.

The Nicaraguan Center for Human Rights says 11 people were killed and 79 injured when pro-government groups attacked protesters at a Mother's Day march led by mothers of those killed in earlier protests. Managua's military hospital tallied two additional deaths and nine wounded.

The country's Roman Catholic church hierarchy said in a statement Thursday that the violence showed that it couldn't yet resume a dialogue between protesters and President Daniel Ortega's government.

Shortly before the attacks Wednesday, Ortega told supporters at a rally that he was committed to peace. Protests began in mid-April in response to changes to the social security system, but expanded to call for Ortega's exit.