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

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.