At least 17 people have died in the Democratic Republic of Congo during protests calling for President Joseph Kabila to step down.
Three of them were police officers, one of whom was burnt alive, according to the Interior Minister, Evariste Boshab.
But opposition groups said 50 people died, with one witness saying police fired live ammunition into the crowd.
Protesters set up barricades and torched cars on one of the main roads in Kinshasa, the country's capital.
The bodies of people who had died were seen lying in the streets after protests ended.
The electoral commission was meant to announce a date for presidential elections, due in November, on Monday, but has said it will not be possible to hold them then.
The opposition says Mr Kabila is trying to delay the elections in order to remain in power beyond his two-term limit, which finishes in December.
Police have made at least 10 arrests, with hundreds of protesters out on the streets, reports BBC Afrique's Poly Muzalia from the capital.
Most schools and shops are closed in Kinshasa, with those not involved in the protests staying inside to avoid any trouble, our reporter adds.
A government-backed effort to work out a solution to the political crisis, called a "national dialogue", has been boycotted by most opposition parties.
Mr Kabila's second term, the maximum allowed under the country's constitution, is due to expire on 20 December.
Last year at least 12 people died in similar protests.
DR Congo has never had a smooth transfer of power since independence more than 55 years ago.