When Borye Kime crept back into the fishing town of Baga in northeast Nigeria in the early hours of Monday, a weak moon shone on a grisly sight. "It is corpses everywhere," he told AFP.
"The whole town smells of decomposing bodies," the 40-year-old fisherman added.
Kime was one of thousands who fled across the border to Chad when Boko Haram fighters stormed his hometown of Baga in Nigeria's far northeast on January 3.
In the days that followed, the town and at least 16 settlements nearby were burnt to the ground.
What happened in the remote north of Borno state is gradually emerging, lending weight to fears that it may be the deadliest attack yet in a six-year insurgency that has killed over 13,000.
On Saturday, another man, Yanaye Grema, said he was forced to hide for three days while the militants ransacked Baga. He eventually fled into the bush under the cover of darkness on Tuesday.
"For five kilometres (three miles), I kept stepping on dead bodies," he said.
Amnesty International said numerous eye-witnesses had described how the Boko Haram militants went from door to door, pulling out young men of fighting age and shooting them dead in the street.
"It is based on these witnesses' testimonies that we are able to say that hundreds of civilians died in the attack, if not more, and thousands have been displaced," said the group's Nigeria researcher Daniel Eyre.
- Piles of bodies -
Kime knew he was taking a risk by returning to Baga but he said he had to go to retrieve life-savings and money given to him for safe-keeping.
"At first I tried to get in from the northern outskirts but I saw flashlights and heard people talking. From the silhouettes, I could tell it was a Boko Haram barricade," he said.
"I withdrew and tried to approach it from the east and again I saw flashlights close to the primary school. It was another security post.
"I moved away and went in by the livestock market, where I saw piles of bodies scattered all over. It was obviously a scene of a massacre."
In the moonlight, he could see that the town was in ruins. His own home was almost totally destroyed by fire but he still managed to retrieve his cash.
"I didn't stay for more than 10 minutes," he said. "By 3:00 am I was in the canoe paddling back to Dubuwa (village, in Chad).
"It was only when I was heading back that fear gripped me. I realised what grave danger I got myself in."
Nigeria's government has claimed that troops were "actively pursuing" the militants as part of an operation to take back control of Baga.
But Kime said there was "not a single soldier in Baga". Others reported seeing troops abandon their posts when Boko Haram attacked, leaving the fighting to civilian vigilantes.
"The vigilantes fought for some time but withdrew because they could not match Boko Haram's heavy weapons," said Mala Kyari Shuwaram, a local chief from Baga who also made it to Dubuwa.
"It was good the vigilantes put up resistance because that gave many of us time to flee Baga and take canoes into Lake Chad, otherwise we would all have been dead.
"I personally aided four fleeing soldiers to get to a boat. They practically swam on my back to the boat several metres off the shore. The soldiers threw away their guns and fled with us."
- Humanitarian fears -
Many of those who escaped made it to islands on Lake Chad. Chief Shuwaram said about 1,000 people, including the four soldiers spent three days on the Lake.
The panicked mass evacuation split families and has increased pressure on already over-stretched local authorities in the border areas of neighbouring Chad, Niger and Cameroon.
"I don't know where my six-year-old son and 10-year-old daughter are. We lost them in the confusion as we tried to flee Baga," said Shuwaram.
"They were separated from the family and we don't know if they're alive or dead," said Shuwaram.
With Boko Haram still holding Baga, hundreds of people are still stranded on the islands, exposed to the cold seasonal wind, the Harmattan, and without food.
"There are now 15,500 people from Baga sheltering in five villages here in Chad. They are here in Dubuwa, Kangallam, Kaywa, Tetewa and Kilbuwa.
"We are being taken care of by Chadian authorities but our number is huge. The food we get is inadequate".