A student has been killed at the University of Khartoum after being hit by a stray bullet amid continuing deadly clashes in Sudan's capital city.

A Facebook post, verified by the BBC, said the body was buried on campus after safe passage off site could not be secured.

Sudan has been rocked by violence since tensions spilled over between the army and a notorious paramilitary force.

Dozens of students remain trapped.

"We buried our friend after getting permission from his family and the university. We were going to get food for the rest of the students," law student Mosaab Sharif, who is sheltering in a building near the campus, told the BBC.

"There were three of us, and then he was hit in the chest. We couldn't even help him. As we were burying our colleague, one of us was hit with a bullet in his hand."

Both the army and a paramilitary group called the Rapid Support Forces (RSF) claim to control key sites in Khartoum, where residents have been sheltering from explosions and gunfire.

"Snipers have been targeting anyone with flash lights. That's why no-one is walking around wearing white clothes to be extra safe," said Mr Sharif.

"We are scared of both sides, the military and the RSF, if they shoot in our direction."

The law student also added that other students had been sleeping in a nearby mosque, when a shell hit the building, injuring two people.

"We are in the middle of a heavy firefight. There are ammunition strikes around us which hit homes.

"The students have been here for three days without food or drink. Their condition is very, very, bad," Mr Sharif explained in a video posted online, as gunfire rang out in the background.

In a separate video circulating widely on social media, another student reveals how dozens of students are sleeping on the floor of a library on campus.

"There's 88 of us including 20 workers, some elderly. The situation is difficult," he said.

"We can't do anything. we don't have any resources and planes are flying by. We are scared of electricity and water cuts."

He went on to say that food and water was running low but that no-one wanted to risk leaving the building.

A Nigerian student in Khartoum, who wished to remain anonymous, told the BBC that she managed to get out but had "never experienced anything like this in her life".

"We woke up to gunshots, it was really scary, we were panicking," she explained, as she fled from her accommodation and was told to get on a crowded bus to a safer location.

She said she managed to speak to her very worried parents.

"I spoke to my mum yesterday but she could literally hear the gunshots from my phone."

Schools and universities are calling on humanitarian organisations to help evacuate dozens of stranded people and students.

But Ghazali Babiker, Sudan's acting director for the medical charity Médecins Sans Frontières, said that even aid agencies trying to help have been cut off.

"With this war no-one can walk out on the street. Everyone is trapped in their location," he said.