CNN  — 

Fierce fighting across Sudan has left hopes for a peaceful transition to civilian rule in tatters. Forces loyal to two rival generals are vying for control, and as is so often the case, civilians have suffered the most.

At least 459 people have been killed and more than 4,000 injured in the unrest so far, according to the World Health Organization, while parts of the capital Khartoum have become a war zone.

A 72-hour ceasefire agreed on by Sudan’s Armed Forces (SAF) and Sudan’s Rapid Support Forces (RSF) came into effect at midnight local time on Tuesday (Monday 6 p.m. ET).

Volker Perthes, the UN Secretary General’s Special Representative for Sudan, said Tuesday that the ceasefire “seems to be holding in some parts; however, reports of sporadic shooting are still coming in as well as reports of relocation of troops.”

Doctors’ organizations and several eyewitnesses said medical facilities were being bombarded with military strikes in targeted attacks. Both sides later denied shelling hospitals, in comments to CNN.

The unrest entered its 12th day on Wednesday as efforts to evacuate foreign diplomats and citizens intensified.

Here’s what you need to know.

A power struggle is at the center of the fighting

At the heart of the clashes are two men: Sudan’s military ruler and head of the army Abdel Fattah al-Burhan and General Mohamed Hamdan Dagalo (widely known as Hemedti), the country’s deputy and head of the Rapid Support Forces (RSF) paramilitary group.

Until recently, the two men were allies who worked together to topple ousted Sudanese President Omar al-Bashir in 2019 and played a pivotal role in the military coup in 2021.

However, tensions arose during negotiations to integrate the RSF into the country’s military as part of plans to restore civilian rule.

The key question: who would be subordinate to whom under the new hierarchy.

These hostilities, sources told CNN, are the culmination of what both parties view as an existential fight for dominance.

Smoke is seen over Khartoum on April 22, 2023 after days of fighting in the Sudanese capital.

Sudan is no stranger to upheaval

It is difficult to overstate how seismic Bashir’s overthrow was. He had led the country for nearly three decades when popular protests that began over soaring bread prices toppled him from power.

During his rule, South Sudan split from the north while the International Criminal Court issued an arrest warrant for Bashir alleged war crimes in Darfur, a separatist Western region.

After Bashir’s ouster, Sudan was ruled by an uneasy alliance between the military and civilian groups.