CAIRO — Sudanese security forces shot and killed four people during anti-coup protests Thursday, a medical group said as thousands marched to denounce the country’s military rulers and demand an immediate transfer of power to civilians.

The Sudan’s Doctors Committee said in a tweet that the four were fatally shot when police fired live ammunition at protesters in Omdurman, the twin city of Khartoum, the Sudanese capital. The committee, which tracks casualties during protests, said the identity of those killed was not immediately known.

Across the Nile River in Khartoum, police fired tear gas at thousands of demonstrators trying to reach the Republican Palace, the military’s seat of power in the heart of the city. Videos showing thousands waving Sudanese flags and running under clouds of tear gas were posted on social media.

Other videos show demonstrators raising banners reading “No Negotiations! No Partnership” — reiterating their opposition to any power-sharing deal with the military rulers.

Sudan’s leading pro-democracy groups — Forces for the Declaration of Freedom and Change and the Resistance Committees — had called for nationwide protest on Thursday to reiterate their demands for a reversal of the Oct. 25 military coup. The takeover upended the East African country’s short-lived transition to democracy following the 2019 ouster of longtime autocratic ruler Omar al-Bashir.

Thursday’s protests also fell on the third anniversary of a 2019 mass rally that forced the generals to sit down at the negotiating table with pro-democracy groups and eventually sign a power-sharing agreement that was expected to govern Sudan during a transitional period, until general elections were to be held. However, the coup last October scuttled this arrangement.