Jameela Al Lafi, 43, from Martuba, south of the hardest-hit area, said her son, 20, helped with the burials.
She said the entire community of Martuba came together to offer assistance, after deadly floods in recent days that killed thousands, with as many as 10,000 missing.
The death toll in Derna rose to 5,300 people on Wednesday morning, the Interior Ministry appointed by the country’s parliament said.
“We have been through wars, ISIS control and conflict – but we've never seen anything like this,” Ms Al Lafi, who runs a nursery, told The National.
ISIS was expelled in 2015, but fierce battles followed between forces of Gen Khalifa Haftar and the Shura Council militant group that had taken over Derna city.
As bad as those times were, Ms Al Lafi says the situation after Storm Daniel is even worse.
“We have seen the worst of it all. Whole families wiped out. Entire buildings disappearing,” Ms Al Lafi, who runs a nursery, told The National.
“There are 10 and 12-storey buildings, with one or two apartments on every floor. Gone.
“Six hundred bodies were buried in the graveyard. They were using an excavator to create big graves so they can bury them all,” she said.
Ms Al Lafi said her sister, Najah, who lives in the city of Derna with her husband and children, fled to her family home on Thursday, after warnings from local authorities about an incoming storm.
There are concerns flooding could reach Libya's second most-populous city, Benghazi.
A member of the Libyan House of Representatives – the legislature of the country's eastern government – told The National Libya was “not equipped” to handle the type of flooding that hit the eastern area on Sunday.
“The situation is tragic. The fear now is that flooding will reach Benghazi,” Intisar Shennib, chair of the women and children's affairs committee in the House of Representatives, said in a voice message sent exclusively to The National.
“The eastern area is completely cut off from other cities nearby and this has caused difficulty in rescue and recovery teams to reach the victims.
“The resources inside Libya aren't enough to face this tragedy.”
Ms Shennib, who is from Derna, has not been heard from since 12pm on Monday, local time. Communications are down in Derna due to the storm.
In the meantime, local efforts have been essential – with some schools being turned into shelters.
In Benghazi, Al Fakhamah Hotel Apartments has opened its doors to receive people left homeless by the flooding.
“We have 50 suites that can fit 300 people,” the son of the hotel's owner, Dr Ali Zarqa'a, an orthopaedic surgeon, told The National by phone.
“We have set up an emergency operations room through which we are co-ordinating with the local authorities.”
“We are yet to receive our first group of people – although many remain stuck. We are receiving people who are unable to take shelter in schools, like the elderly and people with special needs.”
“We will provide them with everything they need.”
Dr Zarqa'a has said he will be providing medical assistance.
More than 1,000 bodies had been recovered from Derna as of Tuesday morning, the eastern government said.
“Bodies are lying everywhere – in the sea, in the valleys, under the buildings,” Hichem Abu Chkiouat, Minister of Civil Aviation in the eastern government, said , shortly after visiting Derna.
“I am not exaggerating when I say that 25 per cent of the city has disappeared. Many, many buildings have collapsed.”
UN aid chief Martin Griffiths said in a post on X, formerly Twitter, that emergency teams were now being mobilised to help on the ground.
The Tripoli-based Government of National Accord has dispatched aid to Derna. Local media said a delegation from the Presidential Council would arrive on Tuesday evening.
Dax Bennett Roque, the Norwegian Refugee Council’s country director for Libya, said the group's team on the ground is reporting a “disastrous situation”, especially for some of the more impoverished communities.
“Communities across Libya have endured years of conflict, poverty and displacement. The latest disaster will exacerbate the situation for these people. Hospitals and shelters will be overstretched amidst the large wave of displacement,” he said.
“Humanitarian aid groups in Libya have been chronically underfunded. Now is the time to show solidarity with the people and help them on the long way back to recovery.”