Multiple explosions have been heard and a huge fire seen in Port Sudan, though the exact locations and causes were unclear, as Sudan’s civil war rocks the previously quiet city for the third day.

Dark plumes of smoke could be seen emerging from the vicinity of the country’s main maritime port in the city, where hundreds of thousands of displaced people have sought refuge.

Al Jazeera’s Hiba Morgan, reporting from the Sudanese capital, Khartoum, said residents in the port city reported that attack drones launched by the paramilitary Rapid Support Forces (RSF) hit a fuel depot and other targets.

“According to the residents, they believe that it was drone strikes by the paramilitary Rapid Support Forces – once again. They targeted a fuel depot in the city but also around the port and the air base,” Morgan said.

The conflict between Sudan’s army and the RSF has created the world’s worst humanitarian crisis, one likely to be worsened by these latest attacks on Port Sudan, where the United Nations and aid agencies, as well as army-aligned government ministries, have set up headquarters.

Attacks on the Red Sea coastal city, which began on Sunday, represent a sharp escalation in fighting, as Port Sudan had remained untouched by ground or air attacks until this week.

On Sunday, a military base in the city, near the country’s only functioning international airport, was struck by drones, which was followed by the targeting on Monday of fuel depots in the city. In both cases, military sources blamed the RSF.

The attacks came after a military source said the army had destroyed an aircraft and weapons depots in the RSF-controlled Nyala airport. The RSF did not claim responsibility for the attacks.

The attacks this week drew condemnation from neighbours Egypt and Saudi Arabia, as well as expressions of concern from the UN.

The war between the army and RSF began in April 2023, triggered by a dispute over a transition to civilian government.

The conflict has displaced more than 12 million people in Sudan and pushed half the population into acute hunger, according to the UN.