KINSHASA, Democratic Republic of Congo — Nearly 300 people were arrested across the Democratic Republic of Congo as two days of protests against President Joseph Kabila appeared to subside on Wednesday, the police said.

Sporadic gunfire rang out over Kinshasa, the capital, and witnesses reported clashes in Lubumbashi, the southeastern mining hub, but nothing on the scale of the violence when youths took to the streets on Tuesday accusing Mr. Kabila of trying to cling to power.

The police said that 275 people had been arrested and that 21 civilians and one officer had been killed in the protests that erupted as Mr. Kabila’s mandate expired without any elections in place to pick a successor. Rights groups earlier gave higher death tolls.

Mr. Kabila and his supporters have denied any plan to retain power and have said logistical problems delayed elections.