Mozambique’s largest hospital said on Friday that at least three people were killed and 66 injured during clashes between police and protesters the previous day over a disputed election.

The fatalities add to at least 18 people killed in earlier protests since the October 9 poll, which the opposition claims was rigged. Some groups have given a higher toll, with Mozambique’s Centre for Democracy and Human Rights reporting 34 deaths overall.

Thursday’s protests were the biggest Mozambique has ever seen against Frelimo, the party that has ruled the southern African state since 1975 and was declared winner of last month’s election by a landslide.

Civil society groups and international observers said the vote did not meet democratic standards, and the country’s Constitutional Council has requested clarification from the electoral commission on discrepancies in the vote count. Frelimo has not responded to requests for comment.

“Of the 66 injured, 57 were possibly caused by firearms, four were caused by falls, three were injured by physical aggression and two were injured by sharp weapons,” said Dino Lopes, director of the adult emergency service at Maputo Central Hospital.

Most of the victims were between 25 and 35 years old, with others as young as 15, he told a press conference.

Thousands of people took to the streets of the capital Maputo on Thursday chanting “Frelimo must fall”, barricading streets with burning tires and throwing rocks.

Reuters journalists saw police officers firing guns in the direction of the crowd, without pointing directly at protesters.

Mozambique police have been accused by human rights groups of using live ammunition against political protesters in the past. The interior minister has defended the police response to recent demonstrations, saying it was necessary to restore public order.